The error message Invalid use of Null may occur when you try to edit a matter, fee, expense, payment, or adjustment. It also may occur when you try to view or print a bill, a prebill, or a report. When you click OK in response to the error message, RTG Bills exits.

This problem occurs when a record in the database contains bad data. A field in the record contains Null, which in database terminology means that the field was not given any value.

For example, a payment record should contain the amount of the payment that was applied to fees, expenses, late charges, and taxes. If none of the payment was applied to taxes, that field should contain a currency amount of zero. But if this field was not set by the program, it will contain Null instead of zero.

Click here to skip further explanation of this problem and go directly to the solution.

Bugs in older versions of RTG Bills are known to cause this problem:

1. RTG Timer transactions
   When RTG Timer Version 2.05 releases transactions to RTG Bills, two fields are not set properly and will contain Null. The problem only occurs if RTG Timer is set to release the transactions directly into the RTG Bills database (on the same computer or over a network), not for standalone operation of RTG Timer.
   
   To avoid this problem, upgrade RTG Bills to Version 2.06.
   
   
2. Deleting a matter
   If you attempt to delete a matter in RTG Bills and the balance due is not zero, the program will offer to create an adjustment transaction to zero the balance due. In versions prior to Version 2.04, this adjustment transaction is defective (the tax amount is Null).
   
   To avoid this problem, upgrade RTG Bills to Version 2.04.
   
   
3. Downgrading to an earlier version
   New versions often introduce new database fields that earlier versions do not understand. For example, taxes were introduced in Version 1.22. If you install Version 1.22 or above, a tax amount field is included in all payment and adjustment transactions. If you were to install an earlier version of RTG Bills and enter payments and adjustments, they would not set a value for the tax amount field, even though that field has been added to your database. As a result, the database software (the Microsoft Jet database engine) will assign the tax amount field a value of Null. This is a standard feature of relational databases.
   
   To avoid this problem, do not "downgrade" to an earlier version of RTG Bills. If you need to install an earlier version after moving to a new computer, for example, apply all subsequent upgrades before you run RTG Bills.
   
   We also offer a CD with the latest version of the program for a small charge. This is called the RTG Bills & RTG Timer Upgrade. By installing the latest version from CD, you avoid the need to install an older version and then to apply one or more upgrades.
   
   RTG Bills and RTG Timer now check the version of the database against the version of the program. They refuse to run if the database has a higher version number. However, this check is not 100% effective in all versions and you should still be careful not to "downgrade" to an earlier version.

In addition to these known problems, it is always possible that a previously-unreported programming error can create a Null value. Report the problem to RTG if you don't believe that the above situations apply to you.

You can download a small program that will quickly fix the bad database records. It puts appropriate "default" values in the fields which now contain Null.

This program also fixes the problem of negative zero matter balances by properly rounding currency amounts in the database to two decimal places. (This problem was corrected in RTG Bills Version 1.25, but your database may need to be fixed if you have used an earlier version.)

The correction program works with RTG Bills Version 2.05 and above. There is a separate correction program for RTG Bills Versions 1.22, 1.23, 1.24, and 1.25. If you have an older version of RTG Bills, you must upgrade before you can use the correction program. Upgrades are discussed on the Support page.

You must save this program, fixbd.exe or fix125.exe, in the same folder as the RTG Bills program. For a standalone computer, this is usually C:\Program Files\Rtgbills for Version 2 and C:\Rtgbills for Version 1. The program is very small, so you can copy it to a floppy disk and take it to another computer if RTG Bills is installed elsewhere.

1. All users should exit from RTG Bills and RTG Timer.
   
   
2. Double-click the program to run it.
   
   If you get this error message,
   
   

   Error opening database:
   [path] \RTGBILLS.MDB
   Could not find file '[path] \RTGBILLS.MDB'.

   it is because you didn't put the program in the folder that contains the RTG Bills database. Move the program to the same folder as the database (the file Rtgbills.mdb) and try again.

3. You will see the RTG Bills Database (or RTG Bills - Fix 1.25) window.
   • Choose File, Fix Matters.
   • When that is done, choose File, Fix Payments and Adjustments.
   • When that is done, choose File, Fix Fees and Expenses.
   
   
   
4. Exit the program either by choosing File, Exit or by closing the program window.

This should solve the problem.

If you still get the error message, note the exact circumstances under which you see the error message and contact RTG.

The database problem described above for RTG Bills rarely occurs in RTG Timer. However, it can happen and we have a program to fix it. It changes Null values in the Discount Percent field to zero. The detailed instructions which follow are essentially the same as the previous instructions for RTG Bills.

The correction program works with RTG Timer Version 2.01 and above. If you have an older version of RTG Timer, you must upgrade before you can use the correction program. Upgrades are discussed on the Support page.

You must save this program, fixtd.exe, in the same folder as the RTG Timer program. For a standalone computer, this is usually either C:\Program Files\Rtgbills if you first purchased Version 2, or C:\Rtgbills if you upgraded from Version 1. The program is very small, so you can copy it to a floppy disk and take it to another computer if RTG Timer is installed elsewhere.

1. Exit from RTG Timer.
   
   
2. Double-click the program to run it.
   
   If you get this error message,
   
   

   Error opening database:
   [path] \RTGTIMER.MDB
   Could not find file '[path] \RTGTIMER.MDB'.

   it is because you didn't put the program in the folder that contains the RTG Timer database. Move the program to the same folder as the database (the file Rtgtimer.mdb) and try again.
   
   
3. You will see the Fix RTG Timer Database window. Choose File, Fix Fees and Expenses. Click OK when it is done.
   
   
4. Exit the program either by choosing File, Exit or by closing the program window.

This should solve the problem.