It looks like it works now.
I moved the "int p1" parameter to the start of the public static void function (pretty sure I've tried it before).
The stored procedure has one parameter in: "IN p1 INT"
The CLR definition has two parameters, to match the function in the DLL: (int p1, IDataReader readers[]).
When calling the procedure like this:
call GetResultSet1(2)
It returns all rows in the example-table where c1=2 (I've also modified the select-statement from the example).
I have no idea why it works, but now it does!
Regards,
Bjarne