Help! Report Model Project doesn't like my primary key

I'm creating a report model in VS2005 I've created my data source fine and I have selected all the tables I want in the report model data view.

The problem is that for one of the tables it is refusing to acknowledge the promary key. If I try to create the report model it compains that the table doesn't have a primary key.

So I went into SQL Management Studio and checked the table, Lo and behold the primary key is there!!! I tried droping the primary key and recreating it but it still says there is no primary ley on the table.

Any ideas?!?Just did some fiddling and managed to find the problem.

There is a Unique Clustered Index on the table which the problem comes from, with the index it doesn't see the primary key, without it the key suddenly appears