The column 'X' either doesn't exist or doesn't have a relationship to any table available in the current context.

RELATED needs an active many-to-one relationship to the target table, and there isn't one.

Why it happens

• No relationship exists between the tables.
• The relationship exists but is inactive.
• RELATED was used from the one-side toward the many-side (that needs RELATEDTABLE).

How to fix it

1. Create or activate the relationship in Model view.
2. From the one-side toward many, use RELATEDTABLE with an aggregator: SUMX ( RELATEDTABLE ( Sales ), Sales[Amount] ).
3. To use an inactive relationship, wrap in CALCULATE ( ..., USERELATIONSHIP ( a, b ) ).