How to fix mouse issue in fear3

Problem:
To use melee we have to press the mouse but my problem when i press the mouse nothing happen, i can't pass the guy at the sliding door, we suppose to melee to get the guy down but i can't get my mouse to melee so i just stuck in there, can't move forward.

Solution:

Change controls for melee attack. When are you close to the enemy does this appear: press or use melee attack - click the middle mouse button.