Dynamics Reverse Face
This is common problem with these kind of collusion objects with dynamics every object has (Back And Front) that is why some time in modeling faces are reversing accidentally , to solve this problem I am writing you this tutorial, so hope it will help you to solve your problem.
So get ready and we are going to start.
1-When you hit play bowling ball is colliding with pins but pins are falling down due to cage face reversed don’t worry we will fix this problem.
The problem is this when you hit play pins are falling down like in the image below.
2-Ok now select the cage and then go to (Display>Polygon Components>Normals, as like in the picture below.
3-Now you should see something link in the image below.
4-Ok go to back side of cage and select the cage and then right click on the cage then chose (Face) as in the picture below.
5-With back face still selected go to (Edit Polygons>Normals>Reverse, in image indicated below.
6-Now hit play you will see none of your pins are falling down every thing ok in the scene. as in the image below.
Hope it helped you to solve your problem.
Please do not hesitate to write me I will be happy to answer you Thanks Aziz Khan.