I can't add Entourage to the dock in osx5.7.-

I have tried all the usual ways dragging the icon from the finder....clicking the icon while the program is running and the icon is in the dock to have it stay there. Nothing works. I was having a problem getting The Sims 2 to stay in the dock but finally it stuck. Oh and I ran disk repair. That made no difference for this problem.

Can anyone help me please. I have searched here and found something about MobileMe and the Dock. I have a trial version of MoblieMe running and I have 5 days to decide wether I want to subscribe. Does anyone know about a conflict between moblieMe and adding things to the dock.

I am sorry this is such a newbie question. But I am a newbie 😛.
Thanks in advance for any help.

Thank you for your suggestion however that doesn't work. No matter how I try to keep it in the dock it will not stay. I have opened the app. and right clicked "keep in dock" I have dragged the icon from the applications folder to the dock ... don't know what else to do.