unity3D StreamingAssets导出后WWW类加载不了。提示出错,路径配置都没问题呀

this.progWWW = WWW.LoadFromCacheOrDownload (Application.dataPath + "/Raw/update_ios", 1);

提示出错信息是这样:
starting www download: /var/mobile/Applications/BD8E15A2-343F-4C7B-88BC-6A006F730AC6/co0001.app/Data/Raw/update_ios
You are trying to load data from a www stream which had the following error when downloading.
unsupported URL

发布的assetBundle放到网络端是可以使用的。

请问谁知道怎么解决~谢谢!

this.progWWW = WWW.LoadFromCacheOrDownload (Application.dataPath + "/Raw/update_ios", 1);
提示出错信息是这样:
starting www download: /var/mobile/Applications/BD8E15A2-343F-4C7B-88BC-6A006F730AC6/co0001.app/Data/Raw/update_ios
You are trying to load data from a www stream which had the following error when downloading.
unsupported URL
发布的assetBundle放到网络