Deploying 2008 application

In deploying my application I had a problem with most of the client machines that generated a cannot find assembly error. A GUID was given as part of the error message so I opened regedit to see and searched for the key with the GUID in the error. I found that it is associated with sqlxml. I had used sqlxml 3.0 in my 2005 application, and when upgrading I used the sqlxml 4.0 version. Updating the clients with the new version fixed the problem.