Guys,

When you start the WX Radar, you need to understand it will display the test pattern for a while.  Nothing will show unless the Weather button is also pressed on EFIS panel.  This button is directly adjacent to the right of the HSI display switch (the one that sets VOR/ILS/MAP/PLAN).

Both the WX radar must be on and the WX switch on EFIS.  Additionally all the correct buttons must be active in the WX Radar panel.

It will only show you weather pertinent to its orientation (I.e. deflect it downward to see what's below your current attitude, etc).  This is not a "real time display", you must wait for the radar to sweep the area and the computer to process the information.

It does work, I use it every flight.  If you still have trouble after this, please specify exactly how you have your related systems configured, and provide a screenshot of your EFIS, WX Radar, and HSI and I'll try to help.