I suspect that your printer is printing the address information, it's most likely that your print is not alligned correctly to actually lay the toner on the envelope.
First, I would start by loading a regular 8.5x11 piece of paper and trying to print the envelope. Basically, you're pretending to print the envelope on regular paper so you can see where/if it's actually printing.
You may find that you have to change the feed orientation in your software, or change it on the envelope.
eg, your printer expects the envelope "feed short edge" but the software thinks it's "feed long edge