Authors CurseForge

My addon, Easy Portal Advert, uses AceGUI to create its help screen. But for some reason, it has stopped working. Every time I use the command to view said help screen, I get this error:

Message: ...terface\AddOns\EasyPortalAdvert\EasyPortalAdvert.lua:400: attempt to index local 'frame' (a nil value)
Time: 03/06/11 10:10:17
Count: 1
Stack: ...terface\AddOns\EasyPortalAdvert\EasyPortalAdvert.lua:400: in function `?'
Interface\FrameXML\ChatFrame.lua:4214: in function `ChatEdit_ParseText'
Interface\FrameXML\ChatFrame.lua:3825: in function `ChatEdit_SendText'
Interface\FrameXML\ChatFrame.lua:3863: in function `ChatEdit_OnEnterPressed'
[string "*:OnEnterPressed"]:1: in function <[string "*:OnEnterPressed"]:1>

I don't understand why this is happening, as the only change I have made to the help, is add in the new commands. Everything is referenced properly in my XML file, as follows:

<Ui xsi:schemaLocation="http://www.blizzard.com/wow/ui/ ..\FrameXML\UI.xsd">
<Script file="libs\LibStub\LibStub.lua"/>
<Include file="libs\AceGUI-3.0\AceGUI-3.0.xml"/>

Everything was working fine in the version of EPA prior to this one, and I've been wracking my brains trying to figure out why it's not working, when I can see nothing wrong with the code (seeing as it was working this time last week).

Any and all help is very much appreciated.

Never mind. Deleting my Cache and WTF folders seems to have fixed the problem.