I can't seem to find how to set a value to NULL in CR.

I need to find the average for a calculated field.  However not all of the records should be included in the calculation so I attempted to create a conditional formula to exclude the records that should not be in the average.  I did this with an If/Then statement.  If the records pass the test, then I calculate the value for that record.  If they don't pass the test, I want the value to be NULL so it isn't factored in the Average. 

the formula looks something like...

If (conditions are met) then   return this calculated value Else NULL

I then add a summary field to the report configured to be the average of the above calculated field.  However, when I omit the Else clause, the value is set to '0.00' which affects the average. 

How would I set the value to NULL or is there another way of accomplishing this?

Thanks in advance!!



Software/Hardware used:
Crystal Reports