[vox-tech] date question

[Peter Jay Salzman]

This works:

   $ /bin/date +'%Y-%m-%d-%H-%M'
   2006-09-28-11-05

This doesn't:

   $ date +'%Y-%m-%d-%H-%M'
   date: extra operand `+%Y-%m-%d-%H-%M'
   Try `date --help' for more information.

Yet, "/bin/date" is the thing I'm running when using an unqualified path:

   $ which date
   /bin/date

If /bin/date is what I'm running, why doesn't this work unless I specifiy
"/bin/date"?

Thanks,
Pete