Anyone who has worked on EP SP2 on WebAS 6.20?

Hi,

I am working on EP6 SP2 on WebAS 6.20

I have created a system.I have tested the connection using System administration > Support > SAP Application > SAP transaction > GUI html

But I get this result

Application URL ':///webgui/!' is not valid! Please check the protocol and host entries for system 'DEV_r3'

So help required?

Thanks & Regards.