Help adding button to OpenMailFrame

[Eldarth]

I'm trying to add a simple text button next to the Reply button in OpenMailFrame, but it's not appearing.
Can anyone nudge me in the right direction? Here's my XML file:

<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/
C:\Projects\WoW\Bin\Interface\FrameXML\UI.xsd">
	<Script file="RKCMailCop.lua"/>	
	<Button name="OpenMailReportButton" parent="OpenMailFrame" inherits="UIPanelButtonTemplate" text="Report">
		<Size>
			<AbsDimension x="82" y="22"/>
		</Size>
		<Anchors>
			<Anchor point="RIGHT" relativeTo="OpenMailReplyButton" relativePoint="LEFT">
				<Offset>
					<AbsDimension x="0" y="0"/>
				</Offset>
			</Anchor>
		</Anchors>
		<Scripts>
			<OnClick>
				RKCMailCop_Report();
			</OnClick>
		</Scripts>
	</Button>
</Ui>

I've tried adding a Frame to my .xml, I've tried inheritng OpenMailFrame, I've even tried adding it thru pure Lua in both my OnLoad portion, and in my GetInboxText() hook area like so:

RKCMailCop_SPAMButton = CreateFrame("Button", "", OpenMailFrame);
RKCMailCop_SPAMButton:SetText("Report");
RKCMailCop_SPAMButton:SetPoint("RIGHT", "OpenMailDeleteButton", "LEFT", 0, 0);
RKCMailCop_SPAMButton:SetScript("OnClick", RKCMailCop_Report);
RKCMailCop_SPAMButton:Show();