What is the meaning of the narrators' saying: "This Hadith has a sound chain of narration, but it is cut off (maqtou')"?

Al-Maqtu’ is that which is attributed to a Tabi’i (successor) or anyone below him, whether it be a saying or an action. Its chain of narration (sanad) may be sound and continuous up to its utterer. Al-Maqtu’ differs from Al-Munqati’; Al-Maqtu’ describes the text (matn) (the words of a Tabi’i or anyone below him), whereas Al-Munqati’ describes the chain of narration (isnad) and means that the chain of narration is discontinuous.