Problems Using Formatdb And Fastacmd

Hello!!

I am having an extremely difficult time with formatdb and fastcmd from NCBI blast.

I am trying to make a db from single mouse chromosome from NCBI using formatdb. Afterwards I try to obtain sequence from defined positions of the db. I use the commands:

formatdb -p F -i 12.fa -o T -t C57Bl6_chr12 -n C57Bl6_chr12
fastacmd -d C57Bl6_chr12 -p T -L 1000000,10001000 -o test.txt

[fastacmd] ERROR: ERROR: Cannot initialize readdb for C57Bl6_chr12 database

It is very annoying that the formatdb is not making the readdb for my file, do you know what I can do about it??

Thanks!!