problems installing leopard on ibook g4

[5pudgun]

Hi,new here and new to macs, hope this is in the correct place.Recently obtained an ibook g4 with 1.07ghz and 768 ram,40 gig hard drive and dvd drive. It's running panther at the moment,but I have leopard install discs and would like to install this. However I keep getting the message osx cannot be installed on this mac,any advice would be most welcome

 

[Consultant]

You cannot use gray disk from another computer to install on a different computer.

You need retail version.

 

[5pudgun]

You cannot use gray disk from another computer to install on a different computer.

You need retail version.

That'll be why then, thank you.