Can't add fields

Just installed Custom Properties for Joomla! 1.5.x, Version 2.0.3 (2010-10-27) but can't add field values to labels. Clicking on the Save and Apply buttons produces no result. Cancel button works. Let me know if you need access to backend. Here are the rest of the system info:

PHP Built on: Linux rs1.websitehostserver.net 2.6.18-374.3.1.el5.lve0.8.44 #1 SMP Mon Oct 3 18:27:54 EEST 2011 x86_64
Database Version: 5.0.92-community
PHP Version: 5.2.17
Web Server: Apache
Web Server to PHP interface: cgi
Joomla! Version: Joomla! 1.5.23 Stable [ senu takaa ama baji ] 04-March-2011 18:00 GMT

Your installation appears to meet or exceed all requirements. Some browsers (IE6 - 8, if I recall correctly) have had problems in past with the buttons that Add / Delete values and with the data submission.
Which browser are you using? Do you get any javascript error?

I'm using Firefox 7.0. I did have 1.9x installed, I upgraded and that's when the problem started so I uninstalled and than installed 2.0 but problem persists.

Haven't heard any replies to my "Quick Reply" — wonder if you got them. This is still a problem and I have to make a decision in the next 24 hour is whether to use CP or not to meet my deadlines. Please help.

I reinstalled Version 1.98.3.6 (2011-10-15) — and it works fine but I would really like to have the features I paid for.

To troubleshoot this problem we need to access your site. We'll contact you privately.