如果在dotnetnuke3.0.13中你使用了Documents，让用户提交文件，你会发现，如果用户只有一个可写的文件夹，用户将不能上船文件
Core module Documents, "Upload New File" don't display untill File location DropDownList changed
When a user has "write to folder"
If the user has two or more folders to write, he still has to select and change the dropdownlist to see the LinkButton! see bellow:
Select the Url for the Document
URL ( A Link To An External Resource )
File ( A File On Your Site )
Root
Upload New File
Open Link In New Browser Window?
解决办法，任何一个用户都给多于一个目录的写权限，或者修改源代码