Ensure the food container you are using is compatible with the EcoLoc lid. If the container is correct and the lid doesn’t fit, the lid might have deformed due to excessive heat from the microwave or dishwasher.Compatible containers are:IKEA 365+ glass food container 1.0 l (art.no. 703.591.99)IKEA 365+ glass food container 1.8 l (art.no. 703.592.03)IKEA 365+ plastic food container 1.0 l (art.no. 403.591.48)IKEA 365+ plastic food container 2.0 l (art.no. 603.591.52)IKEA 365+ plastic food container 4.2 l (art.no. 603.930.66)IKEA 365+ stainless steel/plastic food container 1.0 l (art.no. 094.375.06)Always operate the EcoLoc lids following the user manual.