are you using the webviewer component? The webviewer is no full browser...
You could add a button in App Inventor and use the phone call component alternatively.
or you could use the activity starter to start a full browser to display your page, more info see here
Open the browser to a Web page
Use these activity starter properties to open a specific web page:
Action: android.intent.action.VIEW
DataUri: http://news.google.com