Android :: Displaying ItemizedOverlay(s) On A Map ?

I'm having some troubles with displaying ItemizedOverlay(s) on a map.

Here I extracted a simplified example of what I need to do.

Here's my Map class:

CDE:........

I followed the guide provided by google to extends the ItemizedOverlay class

CODE:...................

As it is clear from the code I need to update at fixed times a map UI with possibly new positions to do so I'm using a timer, but I think I might fall in some kind of thread issues I don't know how to handle, since when running a test I can see in the Log what happens but no marker is drawn on the map.