FYI something I had just discovered the other day with alot of these filters, is some T-SQL functions such as RTRIM do not work, but there are other non T-SQL functions such as TRIM that do work. I haven't found where these are documented, but I thought I'd throw that in there in case you run across the same. You will get an "undefined function" error at runtime if it is bad syntax.
"[Employee Id] = 4 And TRIM([Customer ID]) = 'ERNST'"