NIS problems

[Pierre TILQUIN <tilquin gena ucl ac be>]

Hi,

My PC is turning with RH6.2 and it uses NIS (YP) as name service.
My problem is that I cannot create, as root, directories for users on one
of the partition. I have defined the following partitions :
Filesystem	1k-blocks	Used	Available	Use%	Mounted on	Type
/dev/hda5	1715588	1460812	167628  	90%	/		linux native
/dev/hda3	38890	2446	34436	7%	/boot		linux boot
/dev/hda7	3068160	307392	2760768	10%	/export/home	fat

Although it works in directories of / (e.g. /home or /export), in the
partition mounted on /export/home, I cannot change group-id and user-id for
directories. Example :

/export/home has the following read and write preferences : dwrx r-x r-x
root  root /export/home

/export/home$  mkdir trial
/export/home$  chgrp tilquinp trial
--> operation not permitted
/export/home$  chown gena trial
--> you are not a member of group 'gena': Operation not permitted

However :
- the partition /export/home is well mounted
- tilquinp and gena are defined in NIS tables, not in local files
- ypmatch tilquinp passwd : OK
- finger tilquinp : OK
- groups tilquinp : OK

Finally, I tried to create a directory tilquinp when tilquinp is logged on,
but I don't have the permission. And when I try to change read and write
preferences as root to /export/home by using chmod a+x /export/home, it
doesn't work (nothing is changed).

Since I need to use this partition /export/home as user tilquinp, it would
be nice if someone could help me to solve this problem.
Thanks a lot in advance.

Pierre