Purchased Avast and it said for 4 computers but the license wont work on 2nd one

Why is my license not working when it says 4 computers for 1 year when I bought it?

You might try to email sales AT avast.com and see if they can help you with your license file.

Or click here: http://support.avast.com/index.php?languageid=1&group=eng&_m=knowledgebase&_a=viewarticle&kbarticleid=455#idt_05