I cannot purchase on my games name clash of clan can you help me to follow up my problem, thank you....

If you are getting a message to contact iTunes support then you can do so via this page and ask them why the message is appearing (these are user-to-user forums, we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page

If it's a different problem ... ?

Al you in the US with a US billing address and US iTunes account ?

Then you can only use the Malaysian store - to use the US store you need to be in the US with a US billing address and a US iTunes account