Problem "open In" large files(300 mb) in other apps in iso 6?

[Smith2012]

hi all . i wonder why i cant "open in" large files(300 mb) in other apps in iso 6! for example i can open in small files from idownloader in other app such as dropbox app but if the file size is big it doesn't work! could you guys find a solution for this problem ? i noticed this problem existed from iso 5 onward!