how to call a c++ function with wchar_t[] parameter

[Akademos]

Hi,
I've got a unmanaged C++ DLL which exports 1 function:

extern "C" bool GetDatabaseInfo( UINT uiBuffCnt,
                                 wchar_t wcDataSource[], wchar_t wcCatalog[],
                                 wchar_t wcUsername[], wchar_t wcPassword[] )

Now I've got to call this function from c#. I tried it this way:

[ DllImport( "..\\mydll.dll" ) ]
    internal static extern bool GetDatabaseInfo( uint uiBuffCnt,
                                                 ref string[] sDataSource,
                                                 ref string[] sCatalog,
                                                 ref string[] sUsername,
                                                 ref string[] sPassword
                                               );

string[] sDataSource = new string[1024], 
                 sCatalog    = new string[1024],
                 sUsername   = new string[1024],
                 sPassword   = new string[1024];
 GetDatabaseInfo( 1024, ref sDataSource, ref sCatalog, ref sUsername, ref sPassword );

But the call always fails. Can anyone give me a hint what i did wrong?

Thanks in Advance

Akademos