Prefab missing with perforce?

Hi all! I just started using perforce as version-control tool, and set the connection up well. My case is that I submitted a prefab called p1, and a scene called s1 to the server. Surely, I've already put p1 in s1 before adding them to the server. Then, I created a new workspace and got everything of this project into the new workspace from the server. However, in s1, p1 was missing.... ![alt text][1]

I could find p1 and s1 both in the Assets folder. That is to say I submitted them to the server successfully. As a lot people suggested, I've set project setting as ![alt text][2]

However, it didn't work.... I also tried set version control as Perforce and connected to the server successfully, but I still got the same problem as before...

My unity's version is 5.1.4f1.

Could anybody give me any help please? Thanks in advance!!!! [1]: /storage/temp/57112-111.png [2]: /storage/temp/57113-2222.png