Display a notification if no data found

Hi there

I have some data about employees in a table called 'Referrals', and a separate dimension table for employee names called 'DimEmployee'. The 'Referrals' table does NOT contain information about all employees.

I have a visual holding a sum of all referrals from the 'Referrals' table. 

When you select an employee from a slicer which usese the 'DimEmployee' table, if they are not found in the referrals table, the visual disappears or shows NaN.

I don't mind this, but what I want is a data card perhaps which appears in these circumstances and says 'No referrals found'. 

So almost the opposite of an IF(ISCROSSFILTERED function. I anticipate something like this:

IF(ISNOTFOUND('DimEmployee'),"No referrals found",BLANK()))  But obviously there is no such argument as ISNOTFOUND (I wish there was!)

Help!