I use my enV VX 9900 for work everyday but get tired of using the bluetooth so I bought a set of soft over the ear headphones with a mic. The headphones have the 3.5 jack so I had to buy an adapter to a 2.5 jack for the VX 9900, both the headphones jack and the adapter jack have three rings so the mic should work but I can't seem to make it work, no problems with the headphone but no mic.... What might I be doing wrong? Advise please......JU