unable to open 10.7.5

I'm trying to open OS X Lion 10.7.5 which I downloaded as I need to run Logic 9 music production software, however when I try and open it says that OS X 10.7 won't open it, although I'm aware that doing things in reverse like this is not always possible does anyone know of a way to open it? Do I have to uninstall OS X 10.7 completely? Is Lion just too old? Thanks for reading this.

Where exactly did you download this? 10.7 and 10.7.5 are both Lion.What kind of file is it?

Re-titled thread - your user name as a title gives no one a clue what the post may be about and results in those that may be able to assist possibly not even looking at your question.