If it appears from the answer of the garnishee that he is not indebted to the defendant, and was not so indebted when the writ of garnishment was served upon him, and that he has not in his possession any effects of the defendant and had not when the writ was served, and if he has either denied that any other persons within his knowledge are indebted to the defendant or have in their possession effects belonging to the defendant, or else has named such persons, should the answer of the garnishee not be controverted as hereinafter provided, the court shall enter judgment discharging the garnishee.