provided challange is: Create a Message of The Day component that displays different text based on an attribute...
https://developer.salesforce.com/trailhead/lex_dev/lightning_components/lightning_components_expressions

i completed this challenge but traihead is not accepting it.. it is giving me error. i.e. : 
Challenge not yet complete... here's what's wrong: 
The component is not evaluating the value of the 'DayOfTheWeek' attribute to determine what to display


but when i execute my component it gives me desired output....