Problem with MFJ-432 Voice Keyer

[David L. Thompson" <thompson@mindspring.com (David L. Thompson)]

I just hooked up an MFJ 432 Voice keyer to my Yaesu and all the memories key
the transmitter ok, but cannot transmit straight thru on the mic (Heil boom
mic with HC4).

The manual talks about PTT, but my mic only has the two wires hooked up for
full VOX.  Is this my problem..the QST review also talks about PTT, but I
quit PTT when I left AM in 1963. I did set the XMIT push switch to on which
I assume activates the PTT line from the Voice Keyer to the transmitter.
Doesn't seem to make any difference.

If this is my problem is there a way around it???   

73, Dave K4JRB