Are you sure that the elements in objk array have a field called name? I tried the following which seems to work.
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
<mx:Script>
<![CDATA[
[Bindable]
private var daStates:Array = [
{ name:"Arizona", label:"AZ" },
{ name:"Tennessee", label:"TN" },
{ name:"New York", label:"NY" }
];
]]>
</mx:Script>
<mx:Panel layout="absolute" title="Stack Overflow" id="panel" height="100%" width="100%">
<mx:Form id="daForm">
<mx:FormHeading label="Just a demo" />
<mx:FormItem label="Combo Box">
<mx:ComboBox dataProvider="{daStates}" labelField="name" />
</mx:FormItem>
</mx:Form>
</mx:Panel>
Also, in general its better to use ArrayCollection rather than Array when binding is involved.