Accordingly to a message from Seymour Schlien (many thanks!) I checked from the Internal/Messages trying to find an error. There is no error from EasyABC. The temp midi FILE is created, I can find the file in the hidden directory and I can make it play in any other software than can read midi files. I can also export the tune in a MIDI file (from the menu "File/export/midi) which I can have it played as well.
So to recap, SVG and MIDI files are properly created.
I also test to IMPORT a midi file and it works fine but still cannot be played from within EasyABC.
Accordingly to a message from Seymour Schlien (many thanks!) I checked from the Internal/Messages trying to find an error. There is no error from EasyABC. The temp midi FILE is created, I can find the file in the hidden directory and I can make it play in any other software than can read midi files. I can also export the tune in a MIDI file (from the menu "File/export/midi) which I can have it played as well.
So to recap, SVG and MIDI files are properly created.
I also test to IMPORT a midi file and it works fine but still cannot be played from within EasyABC.