I can't tell by your posting, are you trying to create a circular reference?
Look-up field using the same table you are creating the field in? Well, I'm
going to say it makes sense that it would not be in the list but let me know
if that's what you meant.
On another note... Look-up fields = Bad idea and here's why...
Is the name of the table the first one in the database if you sort them
alphabetically? There's a bug in 2007 where that table won't show up
sometimes. Create a bogus table named A and see if that fixes the problem.