Formatted Search on UDF on outgoing excise form

Hi,

I have added a FMS on a UDF on outgoing excise invoice form.

Query for FMS is

select $[OOEI.DocTotal.Number] +isnull((select SUM(LineTotal) from DLN3  where DocEntry = $[OEI1.BaseEntry.Number]),0)

when I click on FMS it gives following error.

Internal error (-1004) occurred  [Message 131-183]

but if I open base document and again click on FMS then no error occurs and value get changed in UDF.

Thanks.