I want a cell(e28) to highlight green when it equals another cell(g6) containing the results of the sum of a column

I have a cell ( E28 )containing the sum of a column of figures of bank payments that I want to highlight green, when it equals another cell (G6 ) containing the sum of another column of figures of items ordered, I have tries conditional formatting ‘cell value, equal to, $G$6 but no joy, what am I doing wrong?