Semaphore, Shared Memory and IPC Functions

Hi there good folks! Im developing a webbased admintool on a redhat server. Im in need to use the message queing functions. But having a hardtime finding some info on how this works. My apache and php should be configured proerly to. The phpinfo() tells me that sysvsem is a additional module. But as i try to use the semaphore functions i only get the error "Call to undefined function". Can someone pls help me with a way to check out if the server is set up right. (Sample code on a working function) And some information on how this functions work, since they are not documented in the manual I have big problems finding anyone that knows anything about it. All help what so ever is apreciated here. Thx in advance. Greetings Sendron