The LCD reacts to my ear, and puts the speakers on!

After replacement of the LCD, I'm experiencing the following: When receiving calls and puting the phone up to my ear, the speaker turns on. Have to turn the speaker off, but after a while it turns on again. Very annoing. I have tried to change the LCD twice, but still the same happens. Have also changed the proximity sensor, with no better results.. Any suggestions for this. Thanks in advance! Regards Trond/ NORWAY