Extend DHCP pool on Balance20

I’m trying to extend my DHCP pool on my Balance20. I have changed the subnet (from a /24) to be a /23 but I get an error when I attempt to extend the DHCP pool from .1.2 up through .2.250. It says my .2.250 is not in the pool with my .1.2 (which of course is correct - I want to expand the pool)! Please advise!!

Please provide screenshot of your Network Settings (Network > Network Settings) together with the error message.