AR150 DNS value is not being stored?

In the WAN IP settings each time I go to the screen the bottom box (DNS) is empty and in red it has a invalid value message. Even though I have entered this data.

I have also entered 2 DNS sever addresses using the (DNS) button and its separate screen,.

 

Is this normal? I am having selective DNS issues and I did not used to have these.

can you show a screen shot?