"Konrad Banys" wrote:

> hello,
> I've got a problem that can be more or less reliably reproduced.
> I've got a com object described in a c++ written com library. There's
> also an interop for this library. the object has two interfaces. as
> long as use the default interface, everything works fine, but when I
> cast to the other interface and try to execute methods on it, it
> throws the error "QueryInterface failed for interface..."
>
> example:
>
> 1 Strong.Name.InterfaceName i_variable = new
> Strong.Name.InterfaceNameClass();
> 2 Strong.Name.AnotherInterfaceName i_anotherVariable =
> (Strong.Name.AnotherInterfaceName)i_variable;
> 3 i_anotherVariable.someFunction();
>
> The error happens either in line 2 or 3. On the same machine it works
> just fine for a normal (windows forms desktop) application in C# but
> fails in a windows service written also in C#. Declaring the function
> where the code is or the portion of the code as STA does not help.
> Does anybody know a cure?
> Thank You
> Konrad