Object reference not set to an instance of an object.

protected void frmChgRequest_Inserting(object sender, FormViewInsertEventArgs e) {

SqlChgRequest.InsertParameters["ChgID"].DefaultValue = chgIDComplete.ToString();

SqlChgRequest.InsertParameters["RequestDate"].DefaultValue = DateTime.Now.ToString();

}

The error occurs on the first InsertParameters statement. The obvious answer is that the stringbuilder "chgIDComplete" is null, but on debug, it shows a value of "MERCHANT2008115HW". A stringbuilder should have no problem converting to a string. What am I doing wrong?