This shouldn't be so difficult. Dishwasher drain is connected to garbage disposal. Existing rubber connector that connects hose to disposal cracked and was leaking. No problem, just replace the rubber coupling.
Went out and bought a new $2.99 Lasco coupling, slipped one end over the disposal connection and the other over the 1/2" copper pipe that was connected to the 5/8" ID dishwasher hose, and tightened the hose clamps.
The small ID end of the new rubber connector leaks. Things I've tried: replaced 1/2" copper with 1/2" barbed poly; tried different hose clamps; loosened hose clamp; tightened hose clamp. See photo. You can see a drop of water about to drip.
What am I missing? Obviously, the new connector is not sealing around the barbed fitting. Is the barbed fitting just too small? I'm using 1/2", but 3/4" seems too big. Are these connectors known to be oversized such that they're too loose?