How to use If-Then Conditional Across Workbooks in VBA?

I want to use if-then statement across two workbooks.

I've defined x as Long but x does not appear to hold the value of the sum of all cells in column B

But the code looks right, any thoughts?

Sub mycode()

   Dim x As Long


   myRange = Workbooks("Book2").Sheets("Sheet1").Range("B1", _ 
   Range("B1").End(xlDown))


   x = WorksheetFunction.Sum(myRange)    '<<does not seem to hold value



  If Workbooks("Book1").Sheets("Sheet1").Range("A1").Value = x Then

     MsgBox ("values equal")

  Else

     MsgBox ("please review values")

  End If

End Sub