Require a correction in formula

Hi,

"[Microsoft][ODBC SQL Server Driver][SQL Server]Conversion failed when converting date and/or time from character string "

This is error i am getting when i am executing the following Formula in IDT

MSEG.BUDAT between convert(varchar(8),DATEADD(month, DATEDIFF(month,-2,@Select(Mseg\User Date)) - 16,0),112) and convert(varchar(8),DATEADD(month, DATEDIFF(month, -0, @Select(Mseg\User Date)) - 4, 30),112)

This formulae is forfinding material for previous Month.