8.1.5 ItemButtonTemplate Changes

[LudiusMaximus]

I am trying to fix this issue for Altoholic.

We just get this error message when entering the "Character" tab:
"Couldn't find inherited node: ItemButtonTemplate"

So I assume it is due to the xml codes of AuctionHouse.xml (and Mails.xml respectively):

<Ui xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.blizzard.com/wow/ui/">
  <Script file="AuctionHouse.lua"></Script>

  <Button name="AltoAuctionEntryTemplate" virtual="true">
    <Size x="615" y="41" />
    <Layers>
      <Layer level="BACKGROUND">
        <FontString name="$parentName" inherits="GameFontNormal" justifyH="LEFT">
          <Size x="220" y="14" />
          <Anchors>
            <Anchor point="TOPLEFT" x="53" y="0" />
          </Anchors>
        </FontString>
        <FontString name="$parentTimeLeft" inherits="GameFontNormal" justifyH="LEFT">
          <Size x="220" y="10" />
          <Anchors>
            <Anchor point="TOPLEFT" relativeTo="$parentName" relativePoint="BOTTOMLEFT" x="0" y="-2" />
          </Anchors>
        </FontString>
        <FontString name="$parentHighBidder" inherits="GameFontNormal">
          <Size x="160" y="32" />
          <Anchors>
            <Anchor point="TOPLEFT" relativeTo="$parentName" relativePoint="TOPRIGHT" x="5" y="0" />
          </Anchors>
        </FontString>
        <FontString name="$parentPrice" inherits="GameFontNormal" justifyH="RIGHT">
          <Size x="150" y="32" />
          <Anchors>
            <Anchor point="BOTTOMLEFT" relativeTo="$parentHighBidder" relativePoint="BOTTOMRIGHT" x="5" y="0" />
          </Anchors>
        </FontString>
      </Layer>
    </Layers>
    <Frames>
      <Button name="$parentItem" inherits="ItemButtonTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" x="10" y="0" />
        </Anchors>
        <Scripts>
          <OnEnter>
            Altoholic.AuctionHouse:OnEnter(self)
          </OnEnter>
          <OnLeave>
            GameTooltip:Hide();
          </OnLeave>
          <OnClick>
            Altoholic.AuctionHouse:OnClick(self, button)
          </OnClick>
        </Scripts>
      </Button>
    </Frames>
    <Scripts>
      <OnLoad>
        self:RegisterForClicks("LeftButtonDown", "RightButtonDown");
      </OnLoad>
      <OnClick>
        if button == "RightButton" then
          ToggleDropDownMenu(1, nil, AltoholicFrameAuctionsRightClickMenu, self:GetName(), 0, -5);
        end
      </OnClick>
    </Scripts>
    <HighlightTexture name="$parentHighlight" file="Interface\HelpFrame\HelpFrameButton-Highlight" alphaMode="ADD">
      <Size x="555" y="37" />
      <Anchors>
        <Anchor point="TOPLEFT" x="55" y="0" />
      </Anchors>
      <TexCoords left="0" right="1.0" top="0" bottom="0.578125"/>
    </HighlightTexture>
  </Button>

  <Frame name="AltoholicFrameAuctions" parent="AltoholicTabCharacters" hidden="true">
    <Size x="615" y="306" />
    <Anchors>
      <Anchor point="TOPRIGHT" x="39" y="-105" />
    </Anchors>
    <Frames>
      <ScrollFrame name="$parentScrollFrame" inherits="AltoBaseScrollFrameTemplate" hidden="true">
        <Scripts>
          <OnVerticalScroll>
            self:OnVerticalScroll(offset, 41, Altoholic.AuctionHouse.Update)
          </OnVerticalScroll>
        </Scripts>
      </ScrollFrame>
      
      <Button name="$parentEntry1" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentScrollFrame" relativePoint="TOPLEFT" x="0" y="0" />
        </Anchors>
      </Button>
      <Button name="$parentEntry2" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry1" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
      <Button name="$parentEntry3" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry2" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
      <Button name="$parentEntry4" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry3" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
      <Button name="$parentEntry5" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry4" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
      <Button name="$parentEntry6" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry5" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
      <Button name="$parentEntry7" inherits="AltoAuctionEntryTemplate">
        <Anchors>
          <Anchor point="TOPLEFT" relativeTo="$parentEntry6" relativePoint="BOTTOMLEFT" />
        </Anchors>
      </Button>
    </Frames>
  </Frame>
  
</Ui>

I obviously don't understand the concepts at hand.
Simply changing

<Button name="$parentItem" inherits="ItemButtonTemplate">

into

<ItemButton name="$parentItem">

and all the other occurences of "Button" into "ItemButton" just breaks everything:
"...erface\AddOns\Altoholic_Characters\TabCharacters.lua:72: attempt to index global 'AltoholicFrameAuctions' (a nil value)"

Any help would be greatly appreciated. Thanks!