I have a Spark List component with custom Item Renderer. Data provider for the List - Array Collection with 8 elements. Why creation complete of Item Renderer occurs only 7 times? Although the Array Collection of 8 elements and the List displays 8 objects. All this leads to errors in data access (data.myParams).
Because ItemRenderers are recycled. You should override the data accessors of your itemRenderer and then perform any action you want, as it is the moment your renderer gets data from the list.
There : http://help.adobe.com/en_US/flex/using/WS03d33b8076db57b9-23c04461124bbeca597-8000.html