Failed communication between the carriage and the main pca. First check 
the training cables at both ends to make sure they are secure. I would 
remove them and reinsert. If they are you most likely have an issue with
 the cable or the carriage assembly.
It is recommended when you replace 
the carriage assembly that you also replace the trailing cable. If that 
does not solve the issue, the main pca board is your issue.
