changing counter output

I am using NI 6321. I want to create a counter task to output a continuous waveform. ctr0 by default outputs to PFI12 but I need to change it to output to PFI0. I am using C#. I tried using:

DaqSystem.Local.DisconnectTerminals("/Dev2/Ctr0InternalOutput", "/Dev2/PFI12");
DaqSystem.Local.ConnectTerminals("/Dev2/Ctr0InternalOutput", "/Dev2/PFI0");

And in fact it does output the waveform to PFI0 but it is also outputting it to PFI12 which is connected to something else. How can I get it to stop sending the output to the default terminal?