IP & Subnet Calculator

I have used this app for a while and found it useful, until today. I put in several IP addresses - 10.12.131.96/28 and others, and it asks me to enter a valid IP address. Tried restarting and reloading the app and still get the same message

i downloaded this app a few weeks ago & it sat for a minute on the shelf until today. first off, there are a ton of features offered on the free app. living on a returning college graduate budget, this app is a nice chunk of gas/food money but i really dig how the developer lets u know exactly what ur paying for. i plan on purchasing this app on payday soon.

Agree with some terms for a calculator? Really?! Uninstalled immediately