unable to add Records to subgrid

Hello All,

Regarding the Sub grid Issue, When we try to add an existing or new PRS(CUSTOM) record to PRS Subgrid in invoice form, the lookup to select PRS Registrations is available  But once you select PRS registrations the selected registrations are not loaded to PRS Subgrid . Adding a new PRS record from the grid doesn’t update the current invoice Id to Invoice lookup in PRS form.

The relation between Invoice and PRS Registration(Custom Entity) is 1toN we could not find any problem.

Can any one help on this