About enabling ‘file upload button’

Hello.
I’m using DW Question and Answer v1.1.1
I have enabled ‘file upload button’. (http://designwall.com/question/allow-attachments-and-image-upload/)
After then, I can upload files to DW Question and Answers board as a administrator.
And, I gave the ‘upload files’ permission to editor, subscriber groups by using ‘User Role Editor’ plugin.
But they still can’t upload files.
If they try to upload files, they meet an error message.
They can upload files on other menu (e.g : Dashboard -> Media), but on DW Question and Answer plugin, they can’t.
How can I do?