First what you need to check is, if you get flights in the host.
If this is the case then it means that results are filtered on the Resvoyage application. Please check your setup for airline exclusion.
The most common problem here is that you have enabled “Agency working time” functionality on the website settings, but the Time window that you have set is too restrictive.
For example, you set Time window 48 hours, and you get “No flights found” error, try to change time window, put some smaller number like 10 hours, you should get the results.