Troubleshooting a WE 851BT

[Babybearjs]

OK, heres a interesting problem. I have a WE 851BT wall phone and am getting it ready to use. I'm having a problem with the line 1 lamp. when the phone in off hook, and the station key is in the off position, the lamp remains lit. if I hang up the phone the lamp goes off. but whenever I pickup the receiver, the line 1 lamp always goes on... what do I need to check to remedy this.... all the other station lights work as they are suppose to, but line 1 seems to have a problem...