CTS and GND are shorted on the MiniPro IIRC - In fact GND is black, CTS is the second pin. Having CTS grounded means the computer can always send serial even if nothing's listening.
My Sparkfun 5V Basic breakout has CTS going to the chip, not ground. Perhaps there is a different design or yours is shorted - it should still work if CTS is grounded as that's how it would be if plugged into the Mini Pro anyway.
I scrubbed it to get the solder to stick better.
This is worrying, I can't seem to get it to work.