[SAP Cloud Analytics] Building "IF" Formula with Key Figures from different input models

Hi Everyone, I was trying to create an "IF" formula for my story on SAP Analytics Cloud. However, it contains key figures from 2 different input models which I built on Eclipse (1 for sales figures, 1 for number of working days) and I get an error message when I was trying to create the formula, despite I have already linked both models together.

May I know what I can do to create a formula with key figures from different models? Thanks ALL!