Checkout testing errors in PayPal Sandbox

I am trying to test thru PayPal’s Sandbox and when I clicked MarketPress’s check out button I get a couple of errors. The errors show up on the Shipping page.

1st) error

Warning: Invalid argument supplied for foreach() in /home/srush/public_html/hognutscycle/wp-content/plugins/marketpress/marketpress-includes/plugins-shipping/mp-ups.php on line 515

2nd error

The XML document is well formed but the document is not valid

Is this normal with the Sandbox, if not how do I fix this.