Personalizing the Plan in RTC: colorize items by comparsions between time attibutes values, its possible?

I created a release plan in RTC 5.0.2 and applying adjustments to the view editor work breakdown and scheduling. I'm having trouble with the color feature. I need to colorize items in plan whose time spent is higher than the estimated time. I tried to use timeSpent>estimate but did not work. I can use calculation and comparison values to display colors conditionally as a formula? example: timeSpent>estimate && timeSpent<=1.3*estimate , for delays of 30% of the estimated time. Some help?