Google云端硬盘：获取（现有）文件的内容会导致404响应错误

i have a file in my drive that has a "public" visibility. im using the code (below) from the examples page for the drive api to retreive the files content. the file meta data shows me that my file is there. but the hhtp response tells me its not there (The remote server returned an error: (404) Not Found.).(oh by the way the file was uploaded by a user with "owner" permissions, and now im trying to retrieve the same file with a different user with "writer" permissions.)any thoughts?i have a file in my drive that has a "public" v