I've searched and haven't found any info on this.  I have a UDT with 2 currency columns (Total Cost and Deposit).  I also have a True/False column which is to indicate that the Deposit was left.  Finally, I've added a Balance Due column as a Calculated Column.  The Balance Due is either [Total Cost] or [Total Cost]-[Deposit] depending on the True/False Deposit Left column.

I've tried this with the following IIF and it bombs saying that Cannot convert value '' to Type: System.Boolean.

IIF([Deposit Paid],[Total Cost]-[Deposit],[Total Cost])

It appears as though the evaluation is done not based on the value of the column, but rather the content of the column (in this case, the unchecked.gif image)

Is there a way to get this expression to work without having to compare [Deposit Paid] to <img src="/Images/Checked.gif">?