IIS5 at TSE Citrix

Hello, We try to use our Citrix terminal server machine as backup WWW. So we put IIS there and I was trying to set up ISAPI php extension there. I did it several times on our general WWW with the same win2k-server OS there. The book "Professional PHP" by Wrox is a pretty help (no ads, I'm Russian! :) ). And I don't mind. I cannot understand just WHY the ISAPI extension library doesn't load. I know restarting IIS would be necessary, but after the whole server restart I see red arrow near the library at "ISAPI extensions" tab. So I suppose the reason is that the library symbols would be put to something like dynamic symbols cache repository like /etc/ld.so.cache on my Linux box, but our Citrix does interference on this. And, the salt of my question is, does PHP installation as ISAPI require special conditions like reboot the terminal server in "Install mode"? If so, what kind of? and how could I trace that error of loading ISAPI extension? where could I look about logging? the PHP version I tried is 4.2.3. Thanks folks. :)