Import from Excel in NOP v2.50

I am having a little trouble here.  I have downloaded the template that needs to be used for the import from excel in my shopping cart.  I have went through and filled everything in that I can.  Now when I try to import it I get an error everytime.  "Input string was not in a correct format."  

One question that i have is do you leave the titles above the items that you put in excel?  Which file extension should I save it as?  I was thinking .csv but am not sure.

Please help

Thanks

I don't know what you mean by "...import from excel in my shopping cart."   The Product Export is on the Manage Products page.  

In Admin
Create at least one product (or use demo)
Catalog > Products > Manage Products > Export to Excel

This creates a .xlsx file.  Leave it in .xlsx format.

Check the format of the "CreatedOnUtc" field, it must be in the right format, if you dont care about this value leave it empty.