check imei iphone 6

Hi Apple !

I have iphone 6, my friend give for my birthday . But when i check imei of this iphone on

https://selfsolve.apple.com/agreementWarrantyDynamic.do

Say " We're sorry, but we are unable to complete your request at this time. Please try again later."

allway say that. but i check iphone i am using now then have infomation . U can tell me why ?

Thanks your support ^_^