9800White< proximity sensor always activated

[RUSOC]

Hi, i have this problem and i have run to stores and internet but no one cant answer correctly whats the solution.

Every time i replace the touchscreen of a 9800 white, as soon as a call is made the proximity sensor is activated.

There is not any privacy in the touchscreen, i have even remove the adhesive on the touchscreen, change the flex, but still cant fix it. Even replece the screw with new ones.

I have one that used a black one, but as soon as i change it to a white touch, it start the malfuctioning.

I even change between two white touch.

Please help!

thanks.