I'm assuming that when you were trying to use slot 6, you had code that may have looked something like this:
Code:
Solenoid *s = new Solenoid(6, 1);
However, when you tried out module 8 again, you didn't change that. If you try to use a slot other than 8 in the software, it will generate that fatal error. Since by default module 8 is selected, the simplest thing to do is only provide one parameter: the channel number.
Code:
Solenoid *s = new Solenoid(1);