Have you tried making anything float with helium? Sometimes the string is to much for a balloon to lift... The amount of it you would need and the size of the bag needed would be way bigger than what was shown.
Edit:
Apprently the average dog poops like twice a day or about something like .45 pounds per poop on average...
According to https://www.omnicalculator.com/everyday-life/helium-balloons
You would need 17 standard size balloons to lift one poop
Read better man