"Data selector commerce-order:commerce-order-total: for parameter commerce_order is invalid."

I'm trying to set up flat rate shipping rules for Drupal Commerce.

Basically, for 1-3 items ordered the shipping price is $xx, for 4-7 items ordered the shipping price is $yy, etc... When I attempt to order 5 products, it shows me the correct flat rate option selected, but in the shipping costs the flat rate is multiplied by 5, so when it should be $5, it shows $25 for the shipping costs. The shipping rate is supposed to apply to the entire quantity, not each individual item.

Obviously, I set the conditions elements incorrectly, but I can't seem to use any other type of data selector besides: commerce-order. Every other option gives me the error:

The integrity check failed with the following error message: "Data selector commerce-order:commerce-order-total: for parameter commerce_order is invalid."

Someone suggested using: "commerce-order:commerce-order-total:amount", but anything I attempt to put into Flat Rate > Condition > Order > Data selector gives me the "Data selector commerce-order:commerce-order-total: for parameter commerce_order is invalid."

Can someone give me some guidance on this?

Thank you very much.