Export for MS project, wrong data for task duration

We have a problem exporting and reopening a project (gantt) from Projeqtor.
The duration of the tasks don't match.
Example on the first 2 tasks on battached pictures :
- 'Input data definition ' task : 3 days on Projeqtor goes to 0.6day on MS project.
- "Product design" task : 20 days on projeqtor goes 4 days on MS project.
 


Have you ever seen this issues? Do you have a solution to are able to open the datas on MS project with the correct task durations.

Thanks for your help.