Plantronics CS520 Headset setup w/ 7942 set

[BaseBall2000]

Looking for help or a work around
We have a Plantronics CS520 headset connected to a Cisco 7942 set that it seems that no matter what configuration I try that best I can do is receive audio but can not transmit audio and that is when i have the base unit connected to the headset jack on the 7942 with headset button pressed
when connected to the headset jack on the phone nothing works at all...
When I connect a Plantronics C55 model to the same 7942 the CS55 works as expected
Thanks in advance

 

[trvlr1]

In the phone programming, make sure Wideband Headset UI Control and Wideband Headset options are set to enabled and wireless Headset Hookswitch is disabled.
On the headset mine is set to F 3 3 for the slider and two dials (CD530)