Forms :: ComboBox To Pop-up Form To Add Data

I'm working on a db that will track students for a summer camp. One of my fields in my student records (CamperInfo) is "School". Currently, the field is set up as a combobox in the CamperInfo Subform in the FamilyInfo form. I would like the combobox to be able to add schools if the school is not listed by a pop-up when the "add school" (or whatever) is selected.

Code:

Private Sub School_AfterUpdate()
On Error GoTo Err_School_AfterUpdate
Dim strForm As String
If Me.School = "Schools" = True Then
strForm = "Schools"
DoCmd.OpenForm Me.School
Err_School_AfterUpdate:
MsgBox Err.Description
End If
End Sub

As you might have guessed, it doesn't work. no errors, it just doesn't do anything. I added the "Schools" data.