OK, not  a whole lot of information provided here....

Since you're using Dundas you have the option of specifying colors via code. I use a small freeware program which has saved me a lot of headaches: Visual Color Picker 2.6 
You can find it here: http://www.linxexplorer.com/colorpicker.html

This app allows you to specify the RGB (example: (0, 191, 255), you can then go into the bar properties and add those RGB values in. There is a cool trick that you can apply and that is to add a value for the transparency by adding a value from 1 - 255 in front: (125,0, 191, 255).

Allright now to answer your question: If you don't have the ability to programatically address your need for color changes you have one option, please bear in mind that this is a cheesy option but nonetheless you can get away with adding several colors in the advanced tab of the chart properties menu and enter values.

Example if you have six bars and the initial 3 must be red and the rest varied, you could add the following values:

249, 0, 0
249, 0, 0
249, 0, 0
249, 233, 0
0, 20, 249
198, 198, 0

You could pretty things up by adding the translucent values at the beginning of each of the above.

Hope this helps.

Patrick PK.