Hello marwen,
The supported file types for datasets are XLS and CSV only (https://knowage-suite.readthedocs.io/en/6.2/functionalities-guide/basic-data-access/index.html#my-dataset).
I see you are using Knowage 6.2. I take this opportunity to remind you that the latest stable version of Knowage is 7.4. I recommend you to update your installation so that you can take advantage of the new features it offers.
I hope I have been helpful,Regards.
Alberto