Range Expander Not Working with MAC

Question

Have been using two WRE54G Range Expanders for over two years.  However, I wanted to add WEP to my system, but when I did that, the Range Expanders lights went RED.  I tried to access the SETUP, but for some reason I am unable to access it.  In any event, made the classic mistake of trying to fix something that really wasn't broken.  Have spent three chat sessions trying to resolve all the issues and of course, after solving one, another cropped up.  Here's where I'm at right now.  Still cannot access the Range Expander SETUP, but more importantly one of the Range Expanders is now no longer working with the MAC's that we have at home.  My wireless PC works fine, but each time I try to log in one of the MAC's, in the expander territory, it tells me that it's a secure connection, which it's not.  For now, I've unplugged one of the expanders and am only using one downstairs and while I have connectivity upstairs, it's not as good as when the expander was working.
Any thoughts or ideas are appreciated.

Answer 1

OK, my problem has now shifted to another issue.  I did as 'quack' suggested and got both expanders to apparently work, both had two blue lights.  I tried two of the MAC's we have, the third is out of the house at the moment.  Also tried my PC laptop, that worked as well.
I then decided to activate WEP on the wireless router Linksys WRT54G.  Here is where it gets confusing.  Both expanders now have one blue light and one red light, but when trying to connect either of the MAC's it does prompt me for the network key, which once entered, both computers get on the Internet.  It took a while and a re-start for the PC to recognize the network as secure, but once it did and I entered the network key, it too worked. 
What continues to baffle me is that there is no way I'm able to access the web setup for the extenders.  The other routers/etc in my network connect via http://192.168.49.xxx, however when I try this using '240' and/or '241' for the expanders, nothing happens.  If I try to ping those addresses, I get no reply. 
What furthers confuses me, in that reading some of the other posts it seems that the expander actually showed up in your list of 'AVAILABLE WIRLESS NETWORKS', that is not the way mine is now, nor was it ever in that list.  I guess I should just leave well enough alone, since everything seems to be working, but I get the sense, it's not working properly.