Getting error Method 'Range' of object '_Global' failed

[ks100]

I have a script that copies a range of formulas from another workbook into the active workbook, then is supposed to autofill them down to the last row. For whatever reason though I am getting an error on the autofill line:

    Range("B3:G3").Select
    Application.CutCopyMode = False
    Selection.AutoFill Destination:=Range("B3:G" & LastRow)