I don't know your process for validation and I'm not sure of the data types for "Township", "VolStart" And "VolEnd". I am guessing they are all numbers (Long).
So I modified your SQL to be executed in VBA.
(warning: untested code)
Code:
Function IsValidPage(pPageNO As Long, pTownship As Long) As String
Dim rst As DAO.Recordset
Dim sSQL As String
'set default return value
IsValidPage = "In Range"
sSQL = "SELECT dbo_VolumeLookup.Township, dbo_VolumeLookup.VolStart, dbo_VolumeLookup.VolEnd, "
sSQL = sSQL & " FROM dbo_VolumeLookup"
sSQL = sSQL & " WHERE dbo_VolumeLookup.Township = " & pTownship
sSQL = sSQL & " AND " & pPageNO & " Between [VolStart] And [VolEnd];"
' Debug.Print sSQL
Set rst = CurrentDb.OpenRecordset(sSQL)
If rst.BOF And rst.EOF Then
'no records found
IsValidPage = "Not In Range"
End If
rst.Close
Set rst = Nothing
End Function
In an unbound text box, you would use
Code:
=IsValidPage(Me.PageNO, Me.CBOSelTown)