Failed to open nac1.ped.map. (--file expects a filename *prefix*; '.ped' #and '.map' are automatically appended.)

[Michelle GN]

hi,

I'm new at Plink analysis.

I'm struggling to open a .bed file.

I have used the following command:

system("plink --file nac1.ped")

and I got the following error:

PLINK v1.90b7 64-bit (16 Jan 2023)             www.cog-genomics.org/plink/1.9/
(C) 2005-2023 Shaun Purcell, Christopher Chang   GNU General Public License v3
Logging to plink.log.
Options in effect:
  --file nac1.ped

16384 MB RAM detected; reserving 8192 MB for main workspace.
Error: Failed to open nac1.ped.map. (--file expects a filename *prefix*; '.ped'
and '.map' are automatically appended.)

The log file is attached. 

Could you please help me to solve this problem? 

I suspect the error and solution are simple but no idea how to fix them.

Thank you very much,

Best,

Michelle