Challenge not yet complete in My Trailhead Playground2 We created a case but we can't find the expected date in the 'Last_Day_of_Month__c' field. Make sure your formula returns the last day of this month.

Troubleshoot a Formula That Includes Dates

Finally challenge is complete!

Double check formula! Should look like screen shot.

AND

For Custom Field Definition Detail mark visible for all 

Field-Level Security for Profile.

AND

Field Name: Last_Day_of_Month (let it auto fill) 

Challenge instructions of

Field Name: Last_Day_of_Month__c

does not work.