Using a formula as an axis label on an x-y scatter chart
I have a report with an x-y scatter chart and I want to be able to use a Formula Field (called xAxisLabel) in the x axis label. In the Chart Options | Title tab there is a place to enter the text you want for the X-Axis label, how do I include the Formula Field in this text. I have tried the following but each time the text I've entered as the X-Axis label is displayed instead of the result of the Formula Field .
So for example if the Formula Field xAxisLabel returns the text 'ng/ml' I want the x axis label to be 'ng/ml' not ''