Paypal error 10413

Ok first of all, I'm pretty mad at this plugin for giving me this error in the middle of the weekend sale I started. Second, I ordered this plugin and paid $20 for it again hoping for it to resolve this issue, but it did not fix it, and I have wasted $20 I didn't have for the fix which didn't happen.

I get this error every time I try to checkout and so have my customers

There was a problem connecting to PayPal to setup your purchase. Please try again.
10413 - Transaction refused because of an invalid argument. See additional error messages for details. - The totals of the cart item amounts do not match order amounts.

I have checked purchase amounts and shipping, and it doesn't work.

I just added a coupon for $15 off today. I don't know how long this issue has been happening, I could have had sales but I didn't because of this issue I didn't know was happening.

My website is and I am using Marketpress 2.7 and using Paypal express, just redid my Paypal api and inputed the new ones, that didn't help.

Right now, when you try to check out (all items are on which redirects to a product on it won't show the error, I think there is a plugin conflict from showing the error. But I disabled all the plugins and got that specific error, All it said before was the first 2 sentences of the error, and that's what it says now. But like I said when i deactivated all the plugins but marketpress, it still gave me that error. I am angry I spent $20, so once this is resolved, please stick to the money back guarantee and refund the $20 I wasted on this fix that didn't work.