The possible causes are:

1. While programming in high level language, the instrucción "RPT N..., N..." instruction has been programmed, but a programmed block number (N) does not exist.
2. When programming "G66 ... S...E..." in an "Irregular pocket canned cycle with islands (G66) and one of the data defining the beginning or the end of the profiles is missing.

The solution for each cause is:

1. When programming the "RPT N..., N..." instruction, the blocks it refers to must be defined in the same program.
2. Check the program. Place the label for parameter "S" at the beginning of the profile definition and the label for parameter "E" at the end of the profile definition.