Printing envelopes on HP 4345MFC

[Richard D. Williams]

FP 5.7 Centos 6.3

I have successfully printed envelopes to HP printers in the past .

Trying to print envelopes to a HP 4345 MFC and I can not seem to get it 
to work.

I can get the envelope feeder to print, but the printer asks if we have 
the correct stock loaded.
We press OK and the stock gets jammed.

I think the stock size needs to be set.

Does anyone have the print code sequences to get it to work?

Thanks in advance,

Richard D. Williams