problem with audio impotation file

Sorry for asking this to you but I'm a new ardour user. I need some help.

I’m not able to import audio file. I explain you.
When I open “Add existing audio” by right clic on region list I select my wav file and clic on “apply”. Sometime it work (importation in region list is OK) but generally it doesn’t. I dont know why. I tried to switch off Jack and restart it but nothing…
I make test with files that was ok for importation but that doesn’t work after I don’t modify this files.
What happen please I need some help.