Syntax error in 9-line macro ..?

Hi there, I have some C++ programming experience but none in VB, can anyone please tell me what's wrong with this macro?

Sub USD() 
     For i = 1 To 415 
          For j = 1 To 5 
              Dim X As String = Cells(i, j).Value 
              Dim aString As String = Replace(X, " USD", "") 
	      Cells(i, j) = aString 
          Next j 
     Next i 
End Sub