Warning Unable To Open .Nin

I am using the latest version of blast from ftp://ftp.ncbi.nlm.nih.gov/blast/executables/release/LATEST/ for linux. I created the database for Bos_taurus using Formatdb commamd of blast.

agl@agl-desktop:~/blast-2.2.25/data$ formatdb -i Btau.fa -p F -o T database was create sucessfully and working properly in terminal.. but when i am using this database in bioperl programming it showing me balst output with this warning that

[blastall] WARNING: Unable to open Batu.fa.nin
[blastall] WARNING: Unable to open Batu.fa.nin
[blastall] WARNING: Unable to open Batu.fa.nin
[blastall] WARNING: Unable to open Batu.fa.nin
[blastall] WARNING: Unable to open Batu.fa.nin

and this is my program which i am running in terminal..

@params = ('database' => 'Btau.fa','outfile' => 'bla.out',  '_READMETHOD' => 'Blast', 'prog'=> 'blastn');

 $factory = Bio::Tools::Run::StandAloneBlast->new(@params);
 $str = Bio::SeqIO->new(-file=>'test_query.fa' , '-format' => 'Fasta' );
 $input = $str->next_seq();
 $factory->blastall($input);

pl tell me what i am doing wrong.

Thanks Manju Rawat