Cause

You have placed a plug connection with separate male pin and female pin representation in the schematic. A corresponding symbol with a direct connection point was used for male and female pins.

Male and female pins also have the same DT, the same designation for each pair and the corresponding settings for Assignment to male / female pin end property ("male pin end" on the male, "female pin end" on the female). The function definition on one of the male or female pins is, however, set as opposite (on the male pin "female pin, 2 connection points", or on the female pin "male pin, 2 connection points").

Solution

1. Change the function definition in the Properties <...> dialog for the relevant male pin or female pin.
2. For the male pin choose the setting "Male pin, 2 connection points", or for the female plug choose the setting "Female pin, 2 connection points".
3. If required, start a new check run.