Hi Cenda,
Please take a backup copy of that dll.xml. Then use a text editor to carefully copy the Simlink detail into the dll.xml:
<Launch.Addon>
<Name>Navigraph Simlink</Name>
<Disabled>False</Disabled>
<Path>Gauges\NavigraphSimlink.dll</Path>
</Launch.Addon>
as the last entry before
</SimBase.Document
Please let us know how you get on.
Cheers
Ian