Hi,
It seems that you have previous version installed and it is active on your phone.
Uninstall older version first, turn off and back on your phone and and retry.
Answer "YES" if it asks you to terminate some programs.

Use version you need from this post
[Only registered and activated users can see links. ]
unpack with WinRar or WinZip (not 7-zip), copy to your card and run .SIS file.