here is the code, the error occurs on the last line, but it doesn't happen all the time. Just every now and then. Any suggestions:

ThisForm.List1.RowSourceType = 0
ThisForm.List1.RowSource = ''

cReportProcedure = alltrim(rep.rep_prg_nm)

lcDo = "do " + lcRep + " with 'disad', .T., .T., " + ;
alltrim(str(rep.rep_pk)) + ", '" + lcCompanyName + "'"
&lcDo

select rep

ThisForm.List1.RowSourceType = 6
ThisForm.List1.RowSource = 'Rep.rep_ds'