That is not right Yezdi..
You don't need to set "das.usedefaultisolationaddress" when your gateway is pingable. Just define the additional address. This is the only thing you should do:
das.isolationaddress0 = 192.168.22.1
Also wrote an article on this a while ago:
http://www.yellow-bricks.com/2012/05/25/use-dasisolationaddressx/