Character entities not in PDF, font problem?

I've run into a very strange problem.

Using the following:

1 <= a <= 200

When this is processed via XEP 5.5, it just get "1 a 200". With the Apache
FOP, I get what I would 
expect, "1 <= a <= 200". So, I originally thought this must be an XEP issue.

However, using the following:

1 &gE; a &lE; 200

gives the same output in both processors, and it isn't correct. In the PDF, I
get the following...

"1 # a # 200"

I could swear this has worked for me in the past. Could I be missing a font or
something? It 
wouldn't explain why I don't get &lt;'s in XEP, but I'm trying to track both
of these down.

-David