wysiwygPro editor not work after happeing onchange function

I have a problem with wysiwygPro editor. I have selected an item from select box then description of this item display through ajax calling. But i want to display the description into wysiwygPro editor when i select an item from selectbox the wysiwygPro editor will load and display the description through ajax calling.I need help to display the editor through ajax calling. how can i do this? I have tried but editor is not loaded.