Import Sales Order from Excel

Hello guys

I am trying to import a sales line / order from Excel into NAV 2015 with RapidStart.
When I want to apply the package then I get an error message for every line:

"Type NavOption is unknown" on Field "Line No."

Why is it using the NavOption type? In the excel it is an integer (10000, 20000 etc.).
Do you have an idea?

Thanks.

Best regards
Raphi