I demo the sample code “DBRoulette”,and use my Appkey and Appsecret to run, Access type = App folder,but when i build to run picture then show this warning , please give me some instruction to this warning than show the picture,thank you!

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With reference to DropBox Api (Standard API errors)
400 Bad input parameter. Error message should indicate which one and why.
You can further investigate error object for details!