Cannot use eternal list data in workflow to update another list field in SP Designer 2010

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SharePoint2010

I have crated an external content to bring my sql table and created an external list with that table. Now I can even read the external list in the browser. My problem is that I'm not able to use the external list data in my workflow. I'm trying to update a native list field to the external list field. I used to the same process with others native lists but I'm not able to it with the external list. So I don't know if that is possible with external list or I'm just missing something.

Will appreciate to get response from you. Thank you