SYSTEM API NOT ACTIVE

Hi guys,
I am new in vicidialnow and need your help. Indeed, I installed vicidialnow from the CD including the Vtiger 5.0.3 but I upgraded vtiger to 5.0.4 and everything worked well but when I click a number of a contact from vtiger a windows pop up and said : SYSTEM API NOT ACTIVE. I checked the agent API doc but I can not figure out how to activate agent API.Please help me.
Thanks
Daphnee
I am new in vicidialnow and need your help. Indeed, I installed vicidialnow from the CD including the Vtiger 5.0.3 but I upgraded vtiger to 5.0.4 and everything worked well but when I click a number of a contact from vtiger a windows pop up and said : SYSTEM API NOT ACTIVE. I checked the agent API doc but I can not figure out how to activate agent API.Please help me.
Thanks
Daphnee