Arnoldi iterations error

Hi, I am running a photonic crystal simulation in COMSOL. The goal of the simulation is to find the eigen frequencies at different possible K vector (vector defining the floquet periodicity in my structure). The simulation sweeps K from 0 to 1 but I get this error "that maximum number of arnoldi iterations are reached, Increase the dimenison of Krylov subspace. Not all eigen frequencies are returned" and it doesnot proceed until K=1 calculation and stops at K=0.97. Can someone help me understand why this error occurs and how to resolve it?