Filter more than two conditions on beforeget event.

We want to filter More than two conditions on beforeget event ,ex: field A = a or field B = b ,
we use this code:
Me.setAttribute("where","req_dep ='6D6AFDB5AC724CEFB5FDF78A489F576D' or req_person ='599478E276D94954A0BF7E17DEE122C4'")

It works to filter the frame.
but click the form to see contention will show this Error Message:  Failed to get the ItemType.

Anyone could give me a hint about it?