Sometimes you may find some buttons disabled in the simulation (grey coloured).
Just as in real life, certain interventions or actions cannot be done prior to following certain protocols or procedures.
It may also happen if the patient is not correctly positioned for the intervention you want to do, or if his health condition doesn’t allow for that action to be taken.
Try to find the reasoning behind it and imagine the steps you would take if it was a real clinical setting.
Examples of disabled buttons: