I'm working on a variation of the LogOn LogOff table I saw in one of the tech help videos. I've put a text box (not visible, formatted as general date) on the cover page, which opens when the DB is opened. When the DB closes the VBA puts a record on a table leaving the UserLogOff Date/Time blank. When the DB is closed the form unloads and I'm trying to update the record with the UserLogOff Date/Time. I've tried a lot of variations of the following;

    CurrentDb.Execute "UPDATE tblLogOnOff " & _
    "SET tblLogOnOff.UserLogOff = " & "#" & Now() & "#" & _
    " WHERE tblLogOnOff.DBUser = " & UserName & " AND tblLogOnOff.UserLogOn = " & "#" & Logon & "#"

but I can't quite get it. The latest error message states
"Run-time error '3061':
Too few parameters. Expected 2."

I'm thinking it's something with the double, double quotes and I've tried a number of variations. Any help appreciated.  Ed