Using Calculate with Filter on Current Month Column

[terrancecloud]

I am learning Power BI DAX, and would like clarification on how to use Calculate() with filter on a column.  

I created a new data query table and relationship called "Dates" to define CurrentMonth as true/false.  There is also CurrentYear, CurrentWeek, CurrentDay, etc, which gives flexibility for start of week/start of month in the event of a holiday, etc.

Here's my incorrect formula, which results in "0" in the report display field:

Gross Margin % MTD Update = Calculate(
[Total Gross Margin %],
FILTER(Dates,Dates[CurrentMonth]=TRUE)
)

Previously, I was using TOTALMTD, which works. Note that the table Date is different, but both contain the same information:

Gross Margin % MTD = TOTALMTD(
[Total Gross Margin %],
FILTER(ALL('Date'[Date]),'Date'[Date] <= TODAY())
)

How can I update the first formula above?

[terrancecloud · Accepted solution]

Turns out, Filter wasn't a requirement here.  The below returned the expected value filtered just fine: (DAX 101, but it helps to know)

Gross Margin % MTD = CALCULATE(
    [Total Gross Margin %],'dimCalendar'[CurrentMonth] = TRUE()
)

The label for this field was customized to the following, if anyone finds it useful:

Month-to-date = 
    FORMAT(EDATE(TODAY(),0),"mmm mm/01 - ") & 
    FORMAT(TODAY(),"mmm mm/dd")

This returns Mar 03/01 - Mar 03/27.