Hi Andrew,
The function call works just fine in the load event.
BTW, where are you based? Have you seen the classifieds?

>Try putting a reference to the procedure file in the load event of the form, it sounds like it is not finding the S2MS function because the procedure file has been closed along the way somewhere. An alternative to procedure files that seems to fit in with where all this stuff is heading is stored procedures, but of course the same thing happens if you forget to open the database which contains the stored procedure.
>HTH.
>>I've got a UDF called S2MS() sitting in a procedure file which converts seconds (numeric) to a formatted mm:ss string.
>>I had a grid in a form and one of the columns had S2MS(Duration) as the control source. It worked just fine.
>>I moved this grid to a new form, and now the grid comes up blank (but with grid lines and headings). If I remove the S2MS() function from the column and just put in "Duration" it works normally, but of course my seconds are unformatted.
>>Any ideas as to what's happened?
>>
>>I've had this sort of thing several times with different "calculated" columns and I'd love to know what's going on.