运行下面这行代码时报错Not a valid version 4 database

blastp -query pep.fa -db ${db} \

-num_threads 10  -evalue 0.000001 -seg yes -soft_masking true -lcase_masking -max_hsps 1 -max_target_seqs 1\

 -outfmt "6 qseqid sseqid qlen slen pident length  mismatch gapopen qstart qend sstart send evalue bitscore qcovs stitle"\

  -out uniprot.blast.out.tsv