Since the Hydrolock is mostly plastic, cracks can form over time in the sides of the connector. Consider also that improper installation or rough handling can cause cracks to form. A crack in the Hydrolock will likely require replacement, though depending on the size and severity, superglue or epoxy could be used to seal the crack. Shut off the water, remove the Hydrolock connector and inspect it for cracks. Repair or replace as necessary.
The gasket around the inside of the end of the Hydrolock connector could be improperly placed. Shut off the water, remove the Hydrolock connector and check the gaskets. Make sure they are properly placed inside the opening of the Hydrolock. Make sure they are not corroded, missing, cracked or otherwise broken. If they are, the connector will likely need to be replaced, unless a replacement gasket can be found.
Improper instillation could cause the snap not to be fully engaged, allowing water to leak out. Also, rough handling could have caused a snap to become disengaged. Check the Hydrolock and make sure snaps on both ends are firmly in place and not broken.
If the hose was not fully inserted into the Hydrolock during installation, a leak could occur. Also, if the end of the hose is cracked or corroded, it might not make a perfect seal. Remove the hose from the Hydrolock and make sure that it is in good condition. If the hose is cracked or corroded, it may be possible to cut that part off, replace the hose fitting and snap the Hydrolock back together. If the crack is too severe, or you don't have the expertise to replace the hose fitting, a new hose will be needed.