SonarQube Redmine plugin connection error

I try to connect SonarQube to Redmine. SonarQube v.5.1.2 Redmine v.3.1.2

I connected to Redmine server using API key, Project key and Redmine URL successfully.

Then I opened "Issue" in SonarQube and clicked on "More"->"Link to Redmine". After that I had an error:

Impossible to create an issue on Redmine. A problem occurred with the remote server:Project cannot be blank.

What does it mean? But I have not blank project in Redmine. What i`m doing wrong?

Thanks.

Thanks for you answer, Guillaume. Everything on my settings configured correctly and connection works fine.

Finally, I found a solution!

1. I went to: https://your_redmine_url/projects/name_of_project/issues.xml There I can see "project id" and "project name". But before, I used project name (identifier on redmine project settings).
2. I changed "project key" (on sonarqube) from "project name" (example: my_project) to "project id" (example: 12). This field "12" you can see on issues.xml.

And it works! I created an issue on Redmine! There was a problem - in project id field.