Macro problem for absolute reference

Dear big brother and sister,

I have a tricky task. I hope you can give me reply. appreciate your help.

I have the following macro. However, sometimes, it doesn't work, it may be because it doesn't applied on specific sheet. May I ask how can I modify the following macro to let it run on specific sheet only.

Secondly, as you go to sheet "before macro", after I use macro for Sub Absolute() (all cells selected are absolute reference", it returns to VALUE. May I know why?

Thanks

Sub Absolute()
Dim cell As Range
For Each cell In Selection
If cell.HasFormula Then
cell.Formula = Application.ConvertFormula _
(cell.Formula, xlA1, xlA1, xlAbsolute)
End If
Next
End Sub

Sub AbsoluteRow()
Dim cell As Range
For Each cell In Selection
If cell.HasFormula Then
cell.Formula = Application.ConvertFormula _
(cell.Formula, xlA1, xlA1, xlAbsRowRelColumn)
End If
Next
End Sub

Sub AbsoluteCol()
Dim cell As Range
For Each cell In Selection
If cell.HasFormula Then
cell.Formula = Application.ConvertFormula _
(cell.Formula, xlA1, xlA1, xlRelRowAbsColumn)
End If
Next
End Sub

Sub Relative()
Dim cell As Range
For Each cell In Selection
If cell.HasFormula Then
cell.Formula = Application.ConvertFormula _
(cell.Formula, xlA1, xlA1, xlRelative)
End If
Next
End Sub