Add-ons installing problem

Hi guys! i have one big problem. When I download some add-on for Blender- I have 2.57- and install it, it won’t appear among add-ons so I can’t activate it… It doesn’t happens with all of the downloaded add-ons but for most of them… Is there a way to istall them, so I can use them? for example ArraySketch didn’t work for me… thanks

Unless it says it is compatible for 2.57 then most likely it won’t work. There have been numerous changes to the api so the addon will need to be updated to work.

Thanks, but is this the only one reason?

What other reason were you expecting ?

sorry… but I am a little bit new… anyway-thanks…