Recovery doesn´t Work - Recover Datafile using backup controlfile?

Hai,

 i try to recover a database.

After this command:

RECOVER DATABASE UNTIL TIME '2010-04-05:18:00:00' USING BACKUP CONTROLFILE;

the recovery success but i should do a recovery of a datafile.

And there´s the problem. i don´t know how.

if i try this command:

recover datafile 9;

i got the message to use backup controlfile.

and this command:

recover datafile 9 using backup controlfile;

told me, that using is a bad parameter for recover datafile.

does anybody have an idea, how i can fix it?

Or do you need more information to help me?

Thanks a lot!