rps blast database 'formatrpsdb' problem

Hi..

After installing BLAST+ package from ncbi, when i try to build a database for rps blast analysis using:

formatrpsdb -t COG_first -i Cog.pn -o T -f 11 -n COG -S 100.0

it gives following error:

[NULL_Caption] FATAL ERROR: COG0001.smpInput

PssmWithParameters.pssm.intermediateData.freqRatios

Unable to match element in intermediateData. line 24227

[NULL_Caption] ERROR: no data found in file 'COG0001.smp'

although i check all files needed to run the program are available. 

Please suggest a solution.

Thank you,