Edit role is not given for an agent then the message displayed is not specific though refers you to right page "Machines".

Question

Create an environment and add one PC , Now try not giving the role , the finish button is not enabled , Fine but the error message was not specific though it refers to the rightpage upon save and close .

Following was the error msg.
"Before you can save this environment, you must provide the following information:
    Machines"

Just to keep all informed.

Answer 1

Ofcourse there is red flower icon which represents it to be mandatory.

Answer 2

Pramod,

Thank you for reporting this issue. I will file a bug to track this.
If you want to file a bug for issues like this in future, you can use this link: http://go.microsoft.com/fwlink/?LinkID=151484

Thanks.
-Darshan