Unable to write on an empty text block

Please let me know why I am unable to write on an "empty text" block. It's the last step in Tutorial 1; Talk to Me using an Emulator. 

the is empty block checks, if a text block is empty and provides true or false

which means, it does not make sense to use this block here

an empty text block is something else, see below

http://appinventor.mit.edu/explore/ai2/support/blocks/text.html#string

" "

Contains a text string.
This string can contain any characters (letters, numbers, or other special characters). On App Inventor it will be considered a Text object.