OAI-PMH Validation Error BASE

Describe the issue or problem
I am trying to validate journal website at OAI-PMH Basic URL and getting an error message. can anyone suggest what could be the issue.

Steps I took leading up to the issue

  1. Go to : https://oval.base-search.net/
  2. Click on : Input “https://journal.sijss.com/index.php/home/oai” and click onValidate
  3. Scroll down to : XML Validation
  4. See error :

XML Validation

ERROR: Identify response well-formed but invalid: Element ‘{http://www.openarchives.org/OAI/2.0/}OAI-PMH’: No matching global declaration available for the validation root., line 6

ERROR: ListRecords response well-formed but invalid: Element ‘{http://www.openarchives.org/OAI/2.0/}OAI-PMH’: No matching global declaration available for the validation root., line 6

What application are you using?
OJS 3.4.0.1.

Additional information
Screenshot of error message: