Converting date value from text column to date

Question

I am writing DAX expression to compare dates in Power BI and return a result. The problem is one of the columns I am trying to use has text and dates. It is basically a column about a task that either has the string "No Task" or a date if the task was completed. Power BI takes that column as a string, and I am not being able to convert the non-text values to dates in order to compare them with the other date column. Any idea on how to do the conversion?

Thanks