Webservices and DLL's (in third party software)

[Brosert]

I realise that many people have asked very similar questions, however none of the solutions outlined seem to quite fit my problem.

I should point out that I am new to both c# and the very idea of WebServices ....

I have a Webservice that calls a managed (?) DLL from a third party. This DLL in turn requires another DLL (not managed), which appears to me to be C or C++ based.
When I try to run the WebService, I get an error:

System.DllNotFoundException: Unable to load DLL 
 

I have tried playing with the location of the DLL, but I assume the problem is that it needs to be visible on the client, not the server (although at this stage I'm only running it on the one box via VS2008). Is there anyway to include this other DLL so that it is visible to the service?

(I do also have static LIBs, which I think have been written in c++, but I assume they're no good for this particular purpose.....)

I have also tried using DLLImport, but some of the parameters in the methods that would be called from that DLL appear to have parameters that are pointers - which apparently requires unsafe to be declared {and then gives an error message saying I need to set an unsafe flag when compiling - which I can't find how to do....}.

Any thoughts/help much appreciated....