Add-on export XML crossref error

After speaking with support from Crossref, I am transferred to you. Since I can not send the DOI to Crossref through the plugin crossref-xml-export-plugin / (ojs version I have followed this manual and I have everything activated according to the indications.

The error that the plugin throws at me is the following:
Failed to locate the main schema resource at ‘’.

I await your response.

Hi @gardbeat,

Can you verify it your plugin is up to date or you can update it?

Regards, Primoz

Hello @primozs , I have the plugin that brings by default the OJS installation (April 27, 2018 - 11:24). Is there a reliable update?

Thank you and I am waiting.

Hi @gardbeat,

I am using the version that came with the OJS and works, so it make mi thinking the update could help.

Regards, Primož

Hi @primozs .

I could then use the OJS version plugin

Thank you and I look forward to your response.