The answer to 'drain cleaning not working' is that there are several common causes, including a clogged drain, a problem with the drain pipe, or an issue with the drain trap. Symptoms may include slow draining, standing water, or foul odors coming from the drain.
Some potential solutions include using a plunger or drain snake to try to clear the clog, checking for any obstructions in the drain pipe, and ensuring the drain trap is functioning properly. If these DIY methods don't work, it's best to call a professional plumber to diagnose and fix the issue.