Unable to load the image file from streaming assets folder

I facing the problem of loading the image file from streamingassets folder. the code is work when in editor but when i build into IOS the xcode stated the error: “error: unsupported URL”, can anyone tell me what is the problem of my code?

Here is the code i using:
_localFile = new WWW (“fill://” + System.IO.Path.Combine (Application.streamingAssetsPath, _path));
the _path is string with “XXXX.JPG”

**note: the image file is already in the streamingassets folder and the name of image file passed in is correct (i checked several times)
Thank You.

I think in place of fill you want to write file