calculated dimension using ValueList, with another dimension

[#1]

I am trying to make a chart using a calculated dimension valuelist('x','y') and expression which is basically

if (valuelist('x','y') = 'x', ......... )

This woks fine, but it does not work if I add another dimension to the chart. Does the calculated dimension work only if it is the only dimension? I think not. Any idea what else I should try?

Jonathan.