Your system administrator may have set up a firewall that prevents Sherlock from working properly. See your system administrator for information about setting up Mac OS X to work within the firewall.
The IT department claimed that opening ports for non-academic programs puts the network at risk for virus infections and other vulnerabilities. This is the same canned response even after telling these guys that Sherlock is part of the OS X system (in some way).
My school is in bed with Microshaft and Dell, so this doesn't surprise me.