thanks for the reply's ,the console was a good idea : i got the mesage "map not found on server"(i was saving in the wrong dir).It is all working fine now , (i still get this mesage some times, but rarely, could help to know what is causing it, in order to avoid it.A second question is : how does the "Transformation tool " work?I have a problem: at scale ,the smaler the number, the bigger the brush (does it not use "units"?)or I am using the wrong tool to create brushes of specific sizes?Last, I tried experimenting with the light tool , but I can't get it to flicker!!!(I tried all the presets, and the only difference is the color: thungsten or fuorescent )thanks!!