Here's a public function I use to check that required fields are not empty. I'm guessing you want to use select case as each field may have a different kind of validation.
You'll notice in the code below that I test the tags text using instr(). I do this so I can use the tag property in more than one procedure but you could also use this to differentiate what validation to do on that control.
Code:
Public Function frmValid(frm As Form) As Boolean
Dim ctl As Variant
Dim flg As Boolean
Dim strMsg As String
flg = True
For Each ctl In frm.Controls
If InStr(1, ctl.Tag, "V8") Then
If Nz(ctl, "") = "" Then
flg = False
ctl.BorderColor = vbRed
strMsg = strMsg & Space(20) & "* " & ctl.Controls.Item(0).Caption & vbNewLine
Else
ctl.BorderColor = vbBlack
End If
End If
Next ctl
frmValid = flg
If flg = False Then
MsgBox "The following item(s) are required:" & vbNewLine & vbNewLine & strMsg
End If
End Function
HTH