Sending over serialport (to led controller) does not work reliably on Linux

Good afternoon. There is a problem with the library QSerialPort. At first I install library separately. Then downloaded QT 5.1 where it is already included. I wrote a simple program in the AVR microcontroller. When we send "1" LED lights, when we send "0" LED blow out. I checks is with different terminals everything works fine. I wrote a program c #, everything works. In QT, I used a program that goes to the examples of the SerialPort
C:\Qt\Qt5.2.1\5.2.1\Src\qtserialport\examples\serialport\terminal as well, I tried to write himself , the result is the same . In the best case I need to send two times " 1" or twice "0".Sometimes just nothing works . Here is a video work .
http://www.youtube.com/watch?v=16DYA7DW6ic
P.S. See my last commet