Problem load a dll dynamically

Question

Hello All,
I have a webservice application and the following code:

private static Type buildType(string fullNameClass)
{
    Type autType = null;
    AppDomain app = AppDomain.CurrentDomain;
   
    foreach(Assembly assembly in app.GetAssemblies())
   {
     autType = assembly.GetType(fullNameClass);
     if(autType != null)
        break;
   }

   return autType;


}

The problem is that sometimes the app.GetAssemblies() does not return the DLL
expected. Its find the DLL for about an hour and then stop.

Thank for any help.