Hi,
You did not specify the setting but I guess that you have a ligand in water+ion solution, you use PME to describe long range electrostatic and you use a force field that require DispersionCorrection.
Note, that not always energy decomposition is possible. For example if you use PME to describe the long you can not decompose the energy.
see How to decompose enthalpic components using the group energy exclusion scheme?
Best regards
\Alessandra