well, you should not be using 2 insert record behaviors in the same page.
only use one insert record behavior.
Can I ask why you need to use the DataAssist insert record behavior?
In most registration forms, using the Dreamweaver Insert Record behavior is sufficient.
If you are going to use the Data Assist insert record behavior, you cannot use the Dreamweaver check new user name behavior. you will need to use another method of checking the username.
this involves creating a recordset to lookup the username that was entered, and using the Server validation behaviors from css form builder to make sure the recordset does not return any results.
before we get into the steps involved in doing that, though, i would like to determine if it is actually necessary.