trying to run cuffmerge in mac os. when i had 2 samples it worked. when i had 16 it doesnt. it comes up with this error :

Traceback (most recent call last):
  File "/usr/local/bin/cuffmerge", line 580, in <module>
    sys.exit(main())
  File "/usr/local/bin/cuffmerge", line 538, in main
    gtf_input_files = test_input_files(transfrag_list_file)
  File "/usr/local/bin/cuffmerge", line 268, in test_input_files
    g = open(line,"r")
IOError: [Errno 2] No such file or directory: 's1l1transcripts.gtf'

i ran this command : cuffmerge -o /Users/.../cuffmerge/results /Users/.../cuffmerge/merged.txt

i created a folder in which i had all transcripts xxx.gtf files . A .txt file with all names of the xxx.gtf files and a results folder for the cufferge option -o. what is wrong ?

Also tried this command:cuffmerge -o /Users/.../results -p 2 -g /Users/../genes.gtf /Users/../cuffmerge/merged.txt