You haven't indicated that the line of code:

Me.txtUserID = Environ("UserName")

is executing. You will have to figure that out.

I would take out the line:

On Error Resume Next

Also, set VB Editor to "Break on all Errors"

Try this code instead of what you have:

Private Sub cmdNewRecord_Click()

On Error GoTo cmdNewRecord_Click_Err

If Not .NewRecord Then DoCmd.RunCommand acCmdRecordsGoToNew

Me.txtUserID = Environ("UserID")

cmdNewRecord_Click_Exit:

Exit Sub

cmdNewRecord_Click_Err:

MsgBox Err.Number & " - " & Err.Description

Resume cmdNewRecord_Click_Exit

End Sub