>I get a datatype mismatch on the SET FILTER command. TransDt is a date. I'm sure this isn't the way to do this, so any help appreciated.
>

>THISFORM.FilterCondition = THISFORM.FilterCondition + ' AND BETWEEN(TRANSFORM(TransDt),' + TRANSFORM(THISFORM.TransDtBegin) + ',' + TRANSFORM(THISFORM.TransDtEnd) + ')'
>m.FilterCondition = THISFORM.FilterCondition
>SET FILTER TO &FilterCondition
>

You're missing dates designation {}

>THISFORM.FilterCondition = THISFORM.FilterCondition + 
' AND BETWEEN(TransDt,{' + TRANSFORM(THISFORM.TransDtBegin) + '},{' + TRANSFORM(THISFORM.TransDtEnd) + '})'
>m.FilterCondition = THISFORM.FilterCondition

SET FILTER TO &FilterCondition

Assuming you have an index on TransDt.