Need help to use inactive and active relationship simultaneously in dax

[AS1110]

Hello,

I am trying to use active and inactive relationship based on the Primary Key in a single measure to use it on a single visulaization.

Scenario:
If Key is found in Table C  via active realtionship use active relationship in measure to find out sales.
If key is not found via active realtionship then compare Table A key with Table C using inactive relationship 

Tried below measure but this doesnt seem to be working

userrelationship =

if(SELECTEDVALUE('Table B'[Key])=SELECTEDVALUE('Table c'[Key]),[salesnew],

CALCULATE([salesnew],USERELATIONSHIP('Table C'[Key],'Table A'[Key])))

Thanks

[AS1110]

Thanks Much 🙂 @ERD 
This solution worked perfectly for the requirement I had!

[ERD · Accepted solution]

@AS1110 ,

according to your description..

your_measure =
IF (
    SELECTEDVALUE ( 'Table A'[Key] ) IN DISTINCT ( 'Table C'[Key] ),
    [salesnew],
    CALCULATE ( [salesnew], USERELATIONSHIP ( 'Table C'[Key], 'Table A'[Key] ) )
)