RMAN skip command?

[ndisang]

hi guys,
I have a tablespace that I don't want to backup. So I put it offline. Then I have to tell RMAN to skip the offline files. Look at my script below and error stack. Appears RMAN does not recognize skip command? Or how do I specify it?
run
{
allocate channel t1 type 'sbt_tape' parms
'ENV=(DSMI_ORC_CONFIG=/tsm/cfg/clinical1_oracle.opt,
DSMO_FS=tsmob)';
backup database;
skip offline;
backup current controlfile;
release channel t1;
}

RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-00558: error encountered while parsing input commands
RMAN-01005: syntax error: found "skip": expecting one of: "allocate, alter, back
up, beginline, catalog, change, copy, duplicate, debug, execute, endinline, host
, mount, open, plsql, recover, release, replicate, restore, resync, }, set, setl
imit, sql, switch, startup, shutdown, send, validate"
RMAN-01007: at line 7 column 1 file: standard input

[kgb]

Look place of error:

backup database (!!!)
skip offline;

run
{
allocate channel t1 type 'sbt_tape' parms
'ENV=(DSMI_ORC_CONFIG=/tsm/cfg/clinical1_oracle.opt,
DSMO_FS=tsmob)';
backup database (no semicolon)
skip offline;
backup current controlfile;
release channel t1;
}
--------------------------------

backup database (!!!)
skip offline;