DBCC SHRINKFILE EMPTYFILE not emptying Trying to remove an extra database file from a database using EMPTYFILE on SQL Server 2008 R2.

use [MYDATABASE] 
        DBCC SHRINKFILE (MY_DATABASE_7, EMPTYFILE); 
        use master 
        ALTER DATABASE [MY_DATABASE] 
        REMOVE FILE MY_DATABASE_7; 


And getting this error


  Msg 2555, Level 16, State 1, Line 2  Cannot move all contents of file
  "MY_DATABASE_7" to other places to complete the emptyfile operation.


The other database files aren't limited in growth in anyway.
There is more than enough disk space

And there is practically nothing left in the 7th file.



So there is no reason why I can't remove this 7th file. 

Any thoughts as to why SQL Server is rejecting the EMPTYFILE ?
Increasing the size of the other database files by 1GB resolved the problem.