Problem with CSV import catergory name cannot be "

Hi,

I want to change the dimensions for all my products from cm to m. I thought I could easily do this by exporting my products as a .csv, changing the dimensions and re-imoprting my csv into hikashop.
However when I do this I get the error message: Category name cannot be ""
After import all products from my category for my product options have been moved to another category, causing all kinds of trouble with my products which had these options.
The exact same thing happens when I export all my products as a .csv and immediately re-import the .csv without changing anything in the .csv or even opening it.

What can I do to avoid having to alter each product one-by-one in Hikashop and importing a .csv withou messing up my product categories?

Kind regards,
Chris