Why is my zoom tool not working?

This is usually due to a non-English language keyboard layout (German, for example), or other possible keyboard mapping conflicts. Go to your Key Shortcuts tab in Preferences:

• In the Track shortcut category the keyboard shortcut you need to change/delete is “Track Luminance”
• In the Stabilize category the keyboard shortcut you need to change/delete is “Stabilize Y Translation On/Off”. You may also need to change “Remove Current Frame from Fixed Frames”.

This should fix your issue.