The error is with the formatting of your XML, seemingly in line 1.
Code:
<Ui xmlns="http://www.blizzard.com/wow/ui/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.blizzard.com/wow/ui/
..\..\FrameXML\UI.xsd">
</Ui>
should work