Sometimes when setting up your machine and taking off the carriage and putting it back on, one of the clump sensors' metal plates can be tripped. If that is the case, when you turn on your machine the following message will be displayed:
Waiting for carriage connection.... Make sure all the sensors have been cleared
This error message could also show up if one of those two plates get tripped during operation or maintenance. To correct the situation, observe the sensors and make sure both plates are pointing downwards.