trailhead challenge is not working

I have created a dashboard 'Sales Performance' under 'My Private App' and created a third number widget on the Sales Performance dashboard that shows the sum of amount of all lost opportunities. But when I tried to check challenge, I am getting the below error.

"Challenge Not yet complete... here's what's wrong:
Could not find a dashboard with the label 'Sales Performance' and the name 'Sales_Performance'. Please follow the requirements and ensure everything is setup correctly"

I am sure the 'Sales Performance' dashboard is created correctly.