Is it going into fifth gear? Yes the car is trying to go into 4th gear instead of reverse. You need to adjust the shifter cables properly. It will take some time, i had the same problem after a clutch job, senior members here helped me a lot. So give it sometime and adjust the cables, check, adjust again, recheck until it shifts like it should. You might get it into reverse and might loose the first gear. That is also the issue of proper cable setting. If its going into fifth then you only need to adjust the cable in front of the shifter. If it does not shift into fifth either then you need to adjust both of the cables.