DAX Conditional Formatting, return blank icon

Was wondering if anyone could help. 

I have a table with rows of metrics, and for each metric I have a Current year measure and a previous year measure. 

I have a matrix where the rows are metric name and for each row, I want to conditionally format based on whether current year is greater than previous year. Take the below example for reference,

IF(

 HASONEVALUE('Metric'[Metric Name])

SWITCH (

 VALUES ('Metric'[Metric Name]),

"Sales", IF([Sales]>[Sales PY], "TriangleHigh","TriangleLow"), 

"Expenses",IF([Expenses]<[Expenses PY], "TriangleHigh","TriangleLow"),

"Profit",IF([Profit]>[Profit PY],  "TriangleHigh","TriangleLow"),

"TriangleMedium"

))

This works exactly the way I want it to. However, if I have a metric I did not list in the above measure but is in the metric name column, for that metric, it shows the triangle medium icon. 

I would like to make it such that if a metric not mentioned above is present, then to just not show any icon whatsoever. I tried changing the measure to 

IF(

 HASONEVALUE('Metric'[Metric Name])

SWITCH (

 VALUES ('Metric'[Metric Name]),

"Sales", IF([Sales]>[Sales PY], "TriangleHigh","TriangleLow"), 

"Expenses",IF([Expenses]<[Expenses PY], "TriangleHigh","TriangleLow"),

"Profit",IF([Profit]>[Profit PY],  "TriangleHigh","TriangleLow"),

""

))

However, it just shows a broken image link for the metrics not mentioned.