search the datagrid that using lookup column

hi,

i have a datagrid that contain (ie. ID, Office and empName)

the Office and empName are a lookup columns

i did this in add query>>filter (like @empName + '%')

when i do it i get an error (data type errer in expression)

my question is:

i need to create a query for Display Member not for Value Member to the empName, is that possible?