PowerPivot import - data in wrong order

Hi guys,

I just came across the functionality of PowerPivot and I'm now trying to use it to manage multiple Pivot tables. Because the data source file is already very big, I would like to have the PowerPivot tables in a different file. The import of external data via the wizard works okay BUT the order of the data is different to the one of my source file.
For example, if the order of the application number is 7, 5, 9 in the data source, it becomes 9,7,5 when I import it to the data model. The data isn't lost. The import wizard confirms that the correct number of rows are imported and I can find the data as well - just not in the correct order.
This is not the case for all tables. For several smaller tables the import works just fine and the data is in exactly the right order. The problem only occurs with my largest tables.
Do you have any idea what might cause this?

Greetings
Juju

Thank you very much for the advice and the links. I just started PowerPivot and am thankful for any tips that can point me in the right direction. I will give the PowerQuery a try!
Juju