Some values not calculating in a measue

[MichaelRensing]

Hope you can help me figure this one out. I have a table, and I am trying to calculate total area based on the a slicer applied to the page, as well as a weighted value based off the percentage of total area.. The slicer is a drop down to select the year.  I have a measure that is calculating the total area based on the slicer:

Area Total = 
CALCULATE(SUM('DDx Export'[Total area]),
'DDx Export'[Percent reduction] > 0,
ALLSELECTED('DDx Export')
)

 This works, and updates the total based on the slicer. The next measure I am using calculates the percentage of the total area using the following measure:

Percentage of Total Area = (SELECTEDVALUE('DDx Export'[Total area])/[Area Total])

This is where things start to go werid.  The calculation works mostly.  Some of the values are just blank.  Any Idea why this wold be? See image below:

Close to the bottom of the image you can see the area 668,832.80. This should calculate to around 4.4% but it is just blank.
Same thing is happening for weighted Net_pEUI measure, but to a larger degeree. I have attached a link to the file in case that helps.

Download: Sustainability Data.pbix

[MichaelRensing]

@DataInsights 

Thank you.  That did it.  I was also able to update my other calculations using the same methodology. 

[DataInsights · Accepted solution]

@MichaelRensing,

This can be resolved with an explicit measure:

Sum Total Area = SUM ( 'DDx Export'[Total area] )

Adjust your % measure as follows:

Percentage of Total Area = DIVIDE ( [Sum Total Area], [Area Total] )

It's best practice to use explicit measures--they're more robust than implicit measures.