Calulating the Number of Days since the last Date in a column based on a filter

[ddeutschman]

I would like to create a Measure that calculates that last date in a column based on a filter. 

I know I need to use DATEDIFF to calculate the number of days and I can use FILTER to get the relevant rows, but I am unclear how to structure the whole formula.  Here is what I have but it has too many arguments for FILTER.

Days since last Reportable = DATEDIFF(FILTER('UMC Safety Incident Log', 'UMC Safety Incident Log'[UMC Status]="reportable"),'UMC Safety Incident Log'[Date of Incident],TODAY(), DAY)

What would you suggest?

[parry2k · Accepted solution]

Try this:

Days since last Reportable = 
var lastdt = Calulate(max('UMC Safety Incident Log'[Date of Incident]), FILTER('UMC Safety Incident Log', 'UMC Safety Incident Log'[UMC Status]="reportable"))
Return
Datediff(lastdt, ,TODAY(), DAY)

[ddeutschman]

There were some errors in the formula (typos) but it worked to provide the date for the whole data set.