Compare 2 column and print the 3rd value in set analysis

[Ritvik]

I have 2 column Birthday_Month(Includes only month of employee birthdate) and 2nd column Pmonth(includes Present month) 
I need to compare both and give output The name of Employee(Firstname)

I tried using this but this is giving the number that only 1 person Have Birthday But i need Name to be printed

Count({<EmployeeID={"=(Birthday_Month=Pmonth)"}>}FirstName) 

Please help 

Thanks in advance 

[vinieme12]

try 

Dimension

=aggr(if(Birthday_Month=Pmonth,EmployeeID),EmployeeID)  << uncheck include null values for this dimension

=Firstname

[Ritvik]

No its Not working

[Ritvik]

No its not working

[vinieme12]

Dimension

=aggr(if(Birthday_Month=Pmonth,EmployeeID),EmployeeID) << uncheck include null values for this dimension

Measure 

=Maxstring(Firstname)

Or

Dimension

=EmployeeID 

Measure 

=if(Birthday_Month=Pmonth, FirstName)