File Attributes in Win Server 2003

I’m still beginner on Win 2003 Server. Today I try to build 1 multiuser application. But when I try to write the file, I had this message : “The File is read-only protected”. And when I saw the Folder Attributes, its READ ONLY. But the Files in the folder not READ ONLY. And I tried to remove the Readonly in the folder, but when I click Apply&OK, and I saw it again and the Read Only still there. Is it the problem?
PS: I already shared the folder and setting the permissions to Full Access. What is the problem ?? Thank you so much….