embedde Qt app run with unexpected fading color

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http://qt-project.org – hi every one , i have some problem to execute Qt application . it has just already ran & recognized all input devises such as touch screen (tslib worked correctly) , but i have unexpected fading color , i cant see any thing from lcd but just very pale object & widget in there, first i’d think my Fb driver had any bug , but when i used (fbv /address/foo.png) it worked correctly , just Qt app dont have clearly color , some tests in (fbtest) was didn’i shoe clearly , too . what’s the problem ? (HowTos)