Touch don't works in QT5 desktop

[xyaw]

I run the 'ts_print' and 'ts_test' and the touch works.
But I go back the qt5 'desktop' to touch the application icon . There is no response.
Please leave suggestion for me to solve this.

ps. I send the event when touch down in touch driver:
input_report_abs(ts->input_dev, ABS_X, x);
input_report_abs(ts->input_dev, ABS_Y, y);
input_event(ts->input_dev, EV_KEY, BTN_TOUCH, 1);
input_sync(ts->input_dev);