Filter a range where criteria is the result from a function that uses 2-fields in the range

[deecee]

Here is what I've tried. MReg_2 is a function where the result (X) will be either 0, 1, 2. c is a cell (offset of field 28), holding a text entry which is numeric or alpha/numeric (e.g. "17" or "127x" but only the numeric value is used. MDate is a date. OS is win 7, Excel is 2007. I'm hoping this is possible if I can get the syntax correct. Can anyone help?
ActiveSheet.Range("$A$1:$AY$1824").AutoFilter Field:=28, _
Criteria1:=MReg_2(Val(c), MDate) =X, _
Operator:=xlFilterValues

Many thanks in anticipation. Even if it isn't possible, it all adds to the sum of knowledge.

DeeCee