Business Notification

I have BusinessNotification Server Installed on a server_A connecting to the db(SQL) server_B via tcp. I have the services running on server_A with an error saying that “The local computer may not have the necessary registry information or message details”. They have created the two entries in table 9801 on db in server_B, but as soon as I try to open the BusinessNotification Manager from a client , it says that it is impossible to connect the server_A. Is there anybody having some idea? Thank you in advance