When running readcufflinks it returns "0 sample". while building the database it does not give me any error but it is not working.

> cuff_data = readCufflinks('diff_out/')
> cuff_data
CuffSet instance with:
     0 samples
     0 genes
     0 isoforms
     0 TSS
     0 CDS
     0 promoters
     0 splicing
     0 relCDS
Warning message:
call dbDisconnect() when finished working with a connection
> cuff_data
CuffSet instance with:
     0 samples
     0 genes
     0 isoforms
     0 TSS
     0 CDS
     0 promoters
     0 splicing
     0 relCDS

R version 3.4.0

cuffdiff v2.2.1 (4237)

Please let me know what is wrong here.

Thanks