Can we not use balance attribute in custom attribute formula?

Summary:

Hi,

We have to write a formula in calculation of a custom attribute, based on the value of a balance attribute.

example: my balance attribute name is OSP RAG: this is RED based on the file import.

Calculated Attribute: ARCS RAG: My ARCS calculated RAG is AMBER.

Now, we want to create a 3rd custom attribute in ARCS (RAG Rating) considering ARCS RAG and OSP RAG (Worst of both).

IF OSP RAG is RED, ARCS RAG is AMBER, THEN RAG Rating is RED.

IF OSP RAG is AMBER, ARCS RAG is RED, THEN RAG Rating is RED

IF OSP RAG is AMBER, ARCS RAG is GREEN, THEN RAG Rating is AMBER and so on.