Can't create a backup of data of a single table
Just taking a look at postgres documentation and samples I've found this specific case:


  To specify an upper-case or mixed-case name in -t and related
  switches, you need to double-quote the name; else it will be folded to
  lower case (see Patterns). But double quotes are special to the shell,
  so in turn they must be quoted. Thus, to dump a single table with a
  mixed-case name, you need something like:


$ pg_dump -t "\"MixedCaseName\"" mydb &gt; mytab.sql


You can read about it here.