Strange camera behavior

Hi I got a third person camera (ship to target) for my space sim. I use D3DXMatrixLookAtLH(&matView,&vPos,&vLook,&vUp) to set the view. vUp = (0,1,0) vLook = Ship position vPos = 1) Ship position – target position 2) normalize vPos 3) scale vPos according to zoom value 4) add ship position to vPos It work well when my ship is not moving. But when i give it some speed, i got a proportional offset (speed / screen position). The ship is supose to be always right in the middle of the screen but at some point, it’s no longer on the screen! I double check the data and everything seem ok. The camera is the last thing i process in my render function. Do i build the lookAt matrix correctly? Or if it''s not that, someone have an idea how to fix this problem?