title: "No current record" after Cancel in combo_BeforeUpdate
body: <p>I'm trying to prevent circular (or even cascading) references in my data, and it seems it's only working part of the time.</p>
  
  <p>In Access 2007, I have the following table:</p>
  
  <pre><code>create table mfr (
      mfr_id                 Autonumber,
      mfr_nm                 Text(255),
      mfr_is_alias_for_id    Long Integer
  )
  </code></pre>
  
  <p>I'm importing a bunch of data from Excel, and the mfr_nm is one of the columns from the worksheet. I can't control how data gets entered into Excel, so I want a way of capturing alternate spellings as being "really" same thing. So far, so good (I think...).</p>
  
  <p>Now I've built a form off of this table. I've got a ComboBox for the alias--again, so far, so good. However, when I add this code to the BeforeUpdate event, things get "interesting" (error handling omitted):</p>
  
  <pre><code>If Not IsNull(cboMfrAlias) Then
      If Not IsNull(DLookup("mfr_is_alias_for_id", "mfr", "mfr_id=" &amp; cboMfrAlias)) Then
          MsgBox """Alias for"" must not also be an alias.", vbExclamation
          Cancel = True
      End If
  End If
  </code></pre>
  
  <p>This works exactly as I expect it to when the form is in Form View, but if I'm in Datasheet View my MsgBox is immediately followed by an Access-generated "No current record" error that is <strong>not</strong> caught by error handling within the BeforeUpdate sub.</p>
  
  <p>Can I catch this error? Where?</p>