[操作疑難] Cannot install Transmission in DS213j

Dear Ching, I have a problem on install Transmission in DS213j. Appreciate if you could give me a helping hand.

I have installed Transmission last night and downloaded 2 files. Then i moved the "seed monitor" folder. Therefore i try to change setting in transmission Web UI but not found. Finally i try to reinstall Transmission again (the setting will appear while installation), However, it show error message: ...download directory does not exist.

I am sure that the download directory is created. Since i install transmission several times but still fail. It would be great if Ching can give me some valuable advice. Thanks a lot