LINQ/SQL working in SilverLight, but not in SilverLight+SharePoint

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C#

SQL

LINQ

Silverlight

, +

I am developing a SilverLight Web Part for SharePoint 2010 in C#. I have made a LINQ to SQL connection, and it works when I lunch the SilverLight alone.
When I lunch SilverLight as a Web Part in SharePoint it does not work.
What am I doing wrong?

Only SilverLight:
silverlight.png[^]

SilverLight + SharePoint 2010:
silverlight_sharepoint.png[^]