With LEDs, the operating voltage "+" (LED positive) is shared by the red, green, and blue LEDs and the "R", "G", and "B" channels are the ground path. (LED negative)
"R", "G", and "B" control the amount of current flow (more current = brighter) through the red, green, and blue channels of the RGB LED.
By controlling how much current flows through each color channel, the Ultimate I/O controls the LED color.
-- purple = red 255 (full on), green 0 (full off), blue 255
-- Mid-bright white = red 128, green 128, blue 128
maybe randy t is fixing some thing ?
but just hang in there scott will read and step in to help
Why would Randy be working on Andy's Ultimarc site?

Accidently posted before I caught the latest so here's an edit.
my buttons are just single colours (red/blue)
Single-color LEDs only require a single channel (R, G, or B) to light it.
The Ultimate I/O has
no idea what color your LEDs are, only how much current flow in each channel will produce the commanded color.
If you connect a single-color blue LED to the R channel and tell the Ultimate I/O to light the button red, it will allow current to flow through the R channel and light your single-color blue LED.
To keep things simple, wire only one LED per "+RGB" set of pins:
Red LEDs -- wire "+" to LED positive lead and "R" to LED negative
Blue LEDs -- wire "+" to LED positive lead and "B" to LED negative
Scott