Deleting shared memory with ipcrm in Linux

I am working with a shared memory application, and to delete the segments I use the following command:

 ipcrm -M 0x0000162e (this is the key)

But I do not know if I'm doing the right things, because when I run ipcs I see the same segment but with the key 0x0000000. So is the memory segment really deleted? When I run my application several times I see different memory segments with the key 0x000000, like this:

 key        shmid      owner      perms      bytes      nattch     status
 0x00000000 65538      me         666        27         2          dest 
 0x00000000 98307      me         666        5          2          dest 
 0x00000000 131076     me         666        5          1          dest
 0x00000000 163845     me         666        5          0

What is actually happening? Is the memory segment really deleted?

Edit: The problem was - as said below in the accepted answer - that there were two processes using the shared memory, until all the process were closed, the memory segment is not going to disappear.