USERELATIONSHIP function can only use the two columns references participating in relationship

Hi, I have inactive relationships set up between 'MyReport' and 'LegendCategories' table; however, I am still seeing the error 'USERELATIONSHIP function can only use the two columns references participating in relationship' in this code:

Varible = 
SWITCH(
TRUE(),
---------GENDER---------
SELECTEDVALUE(LegendCategories[Field]) = "Gender",
CALCULATE(
[CountPersons], #custom measure to count the number of names in a column
USERELATIONSHIP('MyReport'[Gender], LegendCategories[Category])
),
---------Race---------
SELECTEDVALUE(LegendCategories[Field]) = "Race",
CALCULATE(
[CountPersons], #custom measure to count the number of names in a column
USERELATIONSHIP('MyReport'[Race], LegendCategories[Category])
),
BLANK()
)

I rechecked the relationships, confirmed the spellings, interchanged the syntax of USERELATIONHIP such that 'many' table comes before the 'one' table (as I have 'Many to 1' relationship set here). Nothing seems to be working! Any advice? 

Thanks so much!