Sorry saeedeh, I asked to see the screen shot of your layers panel at 12:42 am. You did not reply until 1:09 am. I did not know when you were going to reply and I grew tired of waiting so I went to bed.
It didn't work before the rasterize because you used shapes made with the shape tools. When you combine two shape layers, it will take on the color of the uppermost layer. If the second shape is smaller than the first, it will appear as if it is gone. It's not. If you look at your paths panel you will see that the second layer/path is within the first.
Here, I have 2 shape layers....
Note that the red shape is within and smaller than the first brown shape.
When combined, I will get what appears to be one red shape.
But if you check your paths panel, you will see that the two shapes have been combined.