After trying to do a build of all of the yui-ext files with JSBuilder I get the following error from firefox:

YAHOO.ext.util has no properties yui-ext-debug.js (line 88),

Line 88: YAHOO.ext.util.Browser = new function(){

Here is the build order I am using for yui-ext-debug.js:

source\Element.js
source\CompositeElement.js
source\DomHelper.js
source\EventManager.js
source\UpdateManager.js
source\CSS.js
source\JSON.js
source\Date.js
source\MixedCollection.js
source\State.js
source\Bench.js
source\anim\Actor.js
source\anim\Animator.js
source\widgets\SplitBar.js
source\widgets\TabPanel.js
source\widgets\Toolbar.js
source\widgets\Resizable.js
source\widgets\BasicDialog.js
source\widgets\DatePicker.js
source\widgets\TemplateView.js
source\grid\Grid.js
source\grid\GridView.js
source\grid\AbstractColumnModel.js
source\grid\DefaultColumnModel.js
source\data\AbstractDataModel.js
source\data\DefaultDataModel.js
source\grid\SelectionModel.js
source\grid\PagedGridView.js
source\grid\GridDD.js
source\grid\EditorGrid.js
source\grid\EditorSelectionModel.js"
source\grid\editor\CellEditor.js"
source\grid\editor\CheckboxEditor.js"
source\grid\editor\DateEditor.js"
source\grid\editor\NumberEditor.js"
source\grid\editor\SelectEditor.js"
source\grid\editor\TextEditor.js"
source\data\LoadableDataModel.js"
source\data\JSONDataModel.js"
source\data\XMLDataModel.js"
source\layout\LayoutManager.js"
source\layout\BorderLayout.js"
source\layout\LayoutRegion.js"
source\layout\SplitLayoutRegion.js"
source\layout\BorderLayoutRegions.js"
source\layout\ContentPanels.js"
source\layout\LayoutStateManager.js"

Does anyone have a clue why I am getting this error?