COUNTIF Containing Date Calculations

Hi Everyone! I hope someone can help me here.

I'm working in a Table where I am tracking maintenance on my boat. File attached.

I have a Date Due column and a Date Completed column.

I display the number of Items Past Due in a Summary section at the top of the sheet above the Table. 

I want to calculate how many items are past their due date, but I also want to make sure that if someone completes a maintenance action and enters the completion date into the Date Completed cell, that the number of items past their due date count is reduced to account for that.

I have tried the below formula but the second COUNTIF function doesn't seem to be subtracted from the first.  When I break it out it returns 0 rather than the number of cells with Date Completed entries later than the Date Due entries. 

I also tried the COUNTIFS function but no luck there either. 

Help please before I go crazy! Thanks!

=COUNTIF(Table1[Date Due],"<="&TODAY())-COUNTIF(Table1[Date Completed],">"&Table1[Date Due])