OpenStreetMap city cannot get extrude hotkey to work

Hi I have been following some youtube tutorials on how to create a city in Blender using OpenStreetMap addon I can import the file no problem but when I try to extrude the flat planes with the E hotkey on my keyboard for extrude it doesnt work I am using the latest version of Blender the extrude hotkey wont work. Can anyone help me out here?
Thanks