Flex: implementing TextInput restrict in spark table gives error

I'm creating a Flex table in which one column is editable. I want to restrict the user's input to certain characters. The following code gives an Could not resolve <s:itemEditor> to a component implementation error. Anyone know how to resolve this?

....
 <fx:Array>
     <supportClasses:MyColumn ... />
     <supportClasses:MyColumn editable="true" ...>
         <s:itemEditor>
             <fx:Component>
                 <s:TextInput restrict="0-9a-zA-Z"/> 
             </fx:Component>
         </s:itemEditor>
     </supportClasses:MyColumn>
     <supportClasses:MyColumn ... />
     ...
 </fx:Array>
 ....
 

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