SQL Server 2005 : Piecemeal restore with fulltext index

[AQSAPFI]

Hi,

I have a problem restoring a Read-Only filegroup in a database.
I've restored the Read/Write filegroups first without any problem.

Then, I am able to recover Read-Only filegroups which do not contain fulltext indexes with the command :
RESTORE DATABASE GSM FILEGROUP = 'FG_RO_20080214' WITH RECOVERY

However, for filegroups containing FullText indexes (Fulltext indexes are in the same filegroup as data used for this index), I always get the following error :

Server: Msg 3149, Level 16, State 6, Line 1
The file or filegroup "sysft_CAT_SM_20080127" is not in a valid state for the "Recover Data Only" option to be used. Only secondary files in the OFFLINE or RECOVERY_PENDING state can be processed.
Server: Msg 3013, Level 16, State 1, Line 1
RESTORE DATABASE is terminating abnormally.

If I'm looking at sys.database_files catalog view, I can see the following
name type_desc state_desc
--------------------- ----------- -----------------
sysft_CAT_MS_20080127 FULLTEXT RECOVERY_PENDING

Does anyone have an idea, please.

Thanks in advance
Patrick