On a merlin magix I have lines 801-815 in pool 890. When I add lines 816-820 to pool 891 or 892. The attendant station starts acting flakey. When you pick up a line or intercom call you can hear the other party but they do not hear me. Lines or SA buttons will not hang up unless I hit the hang up button. If I restore the programming the problem clears. Any help will be appreciated.