Originally I added an application to the dock, and it didn't work. So I changed the location a few times, it still didn't work. – It turned out that when you changed the location, the plist file didn't change in Casper. the Fix is just to delete this dock item, and recreate a new one. then the plist file will be correct.
To add a correct location path, it should be something like this:
file:///Applications/App1.app/
If there is a space, it should be something like this:
file:///Applications/App1%20xxx.app/