1) make sure the "Computer Browser" service is running.
2) If you are going to rely upon network enumeration (that silly green bar when you open the network folder) it may not work on different workgroups or sub nodes of the same network. The fix is pretty simple... in the address bar at the top of the network explorer (NOT the search bar) type the name of the machine you want in UNC style. eg. Link Removed and hit enter. Once you confirm that you can access the machine, just make a shortcut to it. I have a folder in my User folder called "Net Links" where I have my entire network mapped out as shortcuts. This way I don't have to wait the sometimes 10 to 15 minutes for windows to discover things on it's own.