pg_restore: [archiver] input file does not appear to be a valid archive

Hello,

I'm having trouble with pg_dump and pg_restore (PG 7.3.4).

This is how I'm dumping my DB:

# pg_dump -d mydb --clean --inserts --column-inserts --format=P -v -h
localhost -p 5432 -U otis > dbdump

# gzip -9 dbdump + scp it to a remote machine where I want to restore
this dump in a different DB
(same DB user, also on localhost, also PG 7.3.4, but different DB name)

# gunzip dbdump.gz

# pg_restore -a -d myOtherDbName dbdump

But restore fails with this error:

pg_restore: [archiver] input file does not appear to be a valid archive

I checked the man pages for both commands, but didn't see anything that
would make me think that I'm doing something wrong, but I must be....

Thanks,
Otis