If you want help with errors, please post the full error message text and stack trace, if present.

It also helps if you post the relevant code in full. I can't see what you added to the clients list, or what the Client code is, etc., and I don't know what the error details were. I'm not going to guess when I know you could post all that information.

Thus the task is not so much to see what no one has yet seen, but to think what no one has yet thought about that which everybody sees...
E. Schrodinger