ENA _Webin submission portal _ERROR

I have recently uploaded some sequencing runs to the EBI’s ENA database via the Webin submission and upload to their FTP.
All sequencing files were successfully uploaded to their FTP but when I am trying to upload their meta file in Webin submission portal ,getting

ERROR: Failed to find referenced sample, alias.

ERROR: Sample in experiment is null.

how can I successfully submit that data.