Run-time error '11' & Run-time error '1004'

[Piers Clinton-Tarestad]

I have a drop down combobox((name)=AL_MLP) over and linked to cell D:24 with
options of "yes"/"no"/"n/a" to answer a question and if the answer is "no"
or "n/a" i have tried to hide the next question using the following code
(the next question is populated by a similar combobox over and linked to
cell d:25)

Private Sub AL_MLP_Change()
VarCurrentString = AL.AL_MLP.Value
If VarCurrentString = "Yes" Then
AL.Rows("25:25").Select
Selection.EntireRow.Hidden = False
End
End If
VarCurrentString = AL.AL_MLP.Value
If VarCurrentString = "No" Then
AL.Rows("25:25").Select
Selection.EntireRow.Hidden = True
End
End If
VarCurrentString = AL.AL_MLP.Value
If VarCurrentString = "N/A" Then
AL.Rows("25:25").Select
Selection.EntireRow.Hidden = True
End
End If
VarCurrentString = AL.AL_MLP.Value
If VarCurrentString = "" Then
AL.Rows("25:25").Select
Selection.EntireRow.Hidden = False
End
End If

End Sub

this works but the problem is if someone has already skipped forward to the
next question and filled it in then when the user trys to select "no" or
"n/a" the following errors occur

run-time error 11 division by zero

if i ignore this and try again i get

run-time error 1004 unable to set Hidden property of the range class

anybody know how i can fix this as I'm pretty stuck!!!
thanks
piers