Error message when editing OL

Hello,

I am new to Xerte and find it a wonderful tool. Our IT department was able to install it in a server, It is ok to create new learning objects, but when I try to edit the OL I always get an error message "Session ID not set" I do not have much experience on Xerte programming. So, it would be appreciated if anybody could help me to solve this problem.

Best regards,
M Abdulkarim
Westminster Kingsway College