ESI nil monthly return doubt

Dear frds/ experts,

A small Pvt Ltd company presently have no employees. But it is active now. When the employees were in 'no work' condition, it was possible to file Nil ESIC monthly returns. But when all of them exited (Resigned), since it has no employees list, the ESIC portal is not proceeding to file Nil monthly return as earlier. In this situation, plz guide us for further actions to file Nil return. Earliest reply would be greatly appreciated. Thanks in advance.
-Maya.