Problem with sapling Add-On

In the geometry pane the shape drop down is always grayed out like it is inactive and changes do nothing. I’m working through a tutorial that uses this. How do I fix this?

In File / User Preferences / Editing panel, ensure you have ‘Global Undo’ enabled

Global Undo is enabled. Steps = 32. Memory Limit was 1 but changed to 32 with no difference.

Of course it’s not it.
Read the tooltip on the shape drop down and you shall find the answer.

Got it. I was clicking to fast to get the tooltip!

Thanks, Rambo. I actually reinstalled Blender to try and fix this before seeing your answer.