Does Ncbitblastncommandline Reads The Outfmt (Options 6, 7, And 10 ) Correctly?

I am trying to call

tblastn_hits = NcbitblastnCommandline(cmd='tblastn',
                                         query=query_handle,
                                         db=db_handle,
                                         num_threads=6,
                                         evalue=0.001,
                                         outfmt="6 qstart qend evalue bitscore",
                                         dbsize=10000000,
                                         out="%s%s.txt" % (result_handle,orf_name))

But, when i run the script, it ignores anything after 6 in outfmt, so the blast results only have default columns. Is this a problem with the Biopython version or i am doing something wrong?