Writing a string to a cell in excel

I am trying to write a value to the "A1" cell, but am getting the following error:

Application-defined or object-defined error '1004'

I have tried many solutions on the net, but none are working. I am using excel 2007 and the file extensiton is .xlsm.

My code is as follows:

Sub varchanger()
On Error GoTo Whoa
Dim TxtRng  As Range

Worksheets("Game").Activate
ActiveSheet.Unprotect

Set TxtRng = ActiveWorkbook.Sheets("Game").Cells(1, 1)
TxtRng.Value = "SubTotal"

'Worksheets("Game").Range("A1") = "Asdf"

LetsContinue:
    Exit Sub
Whoa:
    MsgBox Err.number
    Resume LetsContinue
End Sub

Edit: After I get error if I click the caution icon and then select show calculation steps its working properly