If Statement - Visual Basic For An Input Form

I am creating a user input form where the user can enter data about what they have eaten on a certain day. I am using radio buttons, so when the radio button has been clicked, it automatically puts something into cell A1. What has been put into cell A1 will then be used to say what is in the combo box named Cbo_FoodItem. I have used the following

With Me.Cbo_FoodItem
If Worksheet("na").Range("A1") = "carbs" Then
Cbo_FoodItem.List = Worksheet("foodtable").Range("B2:B215").Value
End If
End With

However, when i try to test it, i get an error which then highlights the "Worksheet" after IF and says "Sub or Function not defined".
Obviously there is something wrong with the formulae, however i cannot work it out. Please help.
I've only just started using visual basic, but i am starting to get the gist of it.