ITtunes doesn't offer new iOS updates for my iPad 2.

Question

Although I manually checked with the Update button, it states that my iOS 4.3.5 is on the actual state. Any hints?

Answer 1

See if the below helps:
Rename, move, or delete the iOS software file (.ipsw)
iTunes uses "ipsw" files to restore your device. If those  files  are unusable, then try deleting them, renaming them, or moving the file  to a different directory. This will cause  iTunes to  download a new copy of the IPSW.    When a restore issue is specific to a  user, it is likely due to an unusable .ipsw file. If removing the .ipsw file does not resolve a user-specific restore issue, then the issue is caused by other user-specific security software settings or iTunes preferences. Creating a new user  will also cause new .ipsw restore files to be downloaded in the new  user. You can find the ".ipsw" files in these locations:
Mac OS X
iPhone
~/Library/iTunes/iPhone Software Updates
iPad
~/Library/iTunes/iPad Software Updates
iPod touch
~/Library/iTunes/iPod Software Updates
Note: The tilde "~" represents your Home directory.
Windows XP
iPhone
C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPhone Software Updates
iPad
C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPad Software Updates
iPod touch
C:\Documents and Settings\[username]\Application Data\Apple Computer\iTunes\iPod Software Updates
Note: To quickly access the Application Data folder, click Start, and then choose Run. Type %appdata% and click OK.
Windows 7 and Vista
iPhone
C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates
iPad
C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPad Software Updates
iPod touch
C:\Users\[username]\AppData\Roaming\Apple Computer\iTunes\iPod Software Updates
Note: To quickly access the AppData folder, click Start, and then in the search bar type %appdata% and press the Return key.