Newbie needs help with plugin installation

Hi, I am a newbie and I am trying to install the Joomla plugin for the scheduler. I am using Joomla 2.5 and I have installed joomla_com_scheduler_v30_120425.zip successfully. However, when I hit the save button in the back end I get the message "There was error during configuration saving. Last stable configuration restored. Error report saved to “com_scheduler_log.xml”. Also, I cannot see anything on the Access Rights tab on the back end, so that makes me think that something is not set up correctly. (file access settings, etc??)
Is there something else that I need to install? Are there some code changes that I need to make?
I read here that most people have no trouble with this plugin and that it works flawlessly.
Unfortunately, I am not one of them and I need a bit of help to point me in the right direction.
Thanks in advance for any help, comments, advice, etc that you can provide to me.

Hi,
Do you use any specific extensions to control user groups?
Please, try to find file com_scheduler_log.xml.
For some reasons user groups can’t be find in database.

I do not have any extensions that control user groups. This is a new site with not much on it.
Also, I scanned for com_scheduler_log.xml and could not find any file.
Would you like access to the site so that you can view what is there? Let me know how I can PM this to you.
Thanks,
Louver