I am adding a formula residing in "Targeting Parameters" into
"DrListWorkCopy" using autofil into a whole column. When I compile the macro,
I got an error on the auto fill line saying" autofill method of Range class
failed.

Would appreciate some help.

My Codes:

Public Sub CopyFormulaDrListWorkCopy()
Dim Target1Wks As Worksheet, Source1Wks As Worksheet
Dim MBC As Range
Dim LR As Long, FillRange As Range

Set Target1Wks = Sheets("DrListWorkCopy")
Set Source1Wks = Sheets("Targeting Parameters")

With Source1Wks
Set MBC = Source1Wks.Range("D59")
End With

With Target1Wks
LR = Range("A65536").End(xlUp).Row
Set FillRange = Target1Wks.Range(Cells(3, 12), Cells(LR, 12))
MBC.AutoFill FillRange

End With
End Sub