Problem with screen

[HighwayAmerica]

Hey. So I bought mine HT Desire a year ago, and it worked quite well. A month ago I broke the screen and sent it to be replaced but there was a problem with my screen.
When I make a call in the day ONLY ON SUNLIGHT I can end calls myself, but in night or with a lamp etc. I cannot end calls. I can make them, but as soon as I make them the screen goes black and I cant do anything. Also I see a little dust in my top left on the screen, could thet be causing the problem please help!
Thanks

 

[Hadron]

Could be. Sounds like the proximity sensor is not deactivating in low light.

Without taking it apart best you can do is clean the top of the screen (the band with the name HTC on it)