mr_anders_son: Faulty ML card or???...
Maybe, but unlikely...
What products do you have connected to the Masterlink ?
As the Masterlink works on a "Token Ring" principle, if you are using Radio for example, it has control of the bus, to use another source, it must first request to take control of the Masterlink, if it does not get control, then DTV will do nothing.
It is likely that something on your Masterlink is stopping it taking control or the option setting is incorrect which you say you have already checked.