Error is sending receiving message : error code="401"

Hi all I m developping a client based on c# .net for instant messaging using Openfire with the api agsXMPP, authetification goes great for two users but when sending a message I m getting this error in the log file :

5TESTTEST

we can see right there the

is there any one who can tell me where is the problem please ?

Same here, do you manage to solve the problem?