1, check the sealing temperature or have reached the minimum sealing requirements (0-300 degrees).
2. Whether the material of the snack box is consistent with the sealing film.
3. Check whether the heating plate (mold) of the sealing machine is heated normally.
If there is no fault, it is recommended to consult the manufacturer and request technical support.
Free access to fault solutions, Baidu search (line far packaging), I hope to help you.