Excel 2007 : VLOOKUP on FormulaR1C1 problem

I have a file , I just wnat to search "sheet1" "A" columns from "sheet2" "B" columns :

Dim myRowCount As Integer, MyFormula As String

myRowCount = Range("A1").CurrentRegion.Rows.Count

MyFormula = "=VLOOKUP(RC[-1],Sheet2!A:B,2,0)"

Range("B1", "B" & myRowCount).FormulaR1C1 = MyFormula

But it came out the resuit is "VLOOKUP(A1,Sheet2!A: (B) ,2,0)"
the "B" column (B) have parenthese on it ,it make the formula don't work
do I wirte any thing wrong?