SQL Server not using enough memory

Hi,

I have a machine running SQL Server 2008 R2 on Windows Server 2008 Enterprise R2 (64 bit).  The server has 30GB RAM, with SQL Server max memory set at 24GB and min memory at 0.  Whatever demands are placed on the server, total server memory does not rise further than 9GB, even though CPU and page life expectancy both appear to be suffering as a result. 

SQL Server is the only major process running on the server.  Neither task manager nor process explorer reveal any other major processes, but task manager shows 29.8 GB physical memory usage.

Is there anything further at the OS or SQL Server configuration level that I should do to prompt it to use more memory?

Any help greatly appreciated,

Ed.