Index exceeds the number of array elements (0).

I get this error

Index exceeds the number of array elements (0).

Error in Oil_Dilution_MR_Cars_analysis_1904_v1 (line 48)

timeseriesMatPurgeRequest{i}{I}.(A{J}).signals.values =

timeseriesMat.drives{i}.(A{J}).signals.values(PurgeRequestIdx{i}(PurgeRequestStartIdx{i}(I)):PurgeRequestIdx{i}(PurgeRequestEndIdx{i}(I)));

Not sure why??

Appreciate thoughts

for I =1: NumPurgeRequest{i}
            disp(['Processing all data for purge request ' num2str(I)])
            A={'ExM_tEgFld_ele2' 'ExM_mfEgFld_ele1','ExM_tWallFld_ele1','EngM_rNOxEngOut','eloil_eot','Outside_Air_Temp_Stat','Tra_numGear','Exh_tPFltUs','Exh_tOxiCatUs','Ignition_Status','InjCrv_phiPoI2Des','InjCrv_phiPoI1Des','AFS_dm','ThrVlv_rAct','NSC_dstLstDNOxRgn','InjCrv_phiPiI1Des','InjCrv_phiPiI2Des','CoEOM_numOpModeAct','EGRVlv_rAct','EGRVlvLP_rAct','CEngDsT_t','ApedPos_Pc_ActlArb','Epm_nEng','ATSys_dstLstRgn__0_','AirMon_dmAFSFlt_mp','PthSet_trqInrSet','ExM_mStrSOx_ExEle','ExM_mStrNOx_ExEle','LSU_rLam__1_','LSU_rLam__0_','ExM_tEgFld_ele3','ExM_tEgFld_ele4','ExM_tEgFld_ele6','ExM_mStrSot_ExFld__1_','ExM_ldSot_ExFld__0_','ExM_ldSot_ExFld__1_','Oil_tSwmp','EngDa_tEng','ATSys_noRgnAcvRul','ATSys_noATSysRgnReq','elomm_w_fio_out_01','eloil_vmo_oil_eng','OdometerMasterValue','VehV_v','InjCrv_qPoI1Des_mp','InjCrv_qPoI2Des_mp','InjCrv_qMI1Des','InjCrv_qMI1Set'};
            for J=2:numel(A)             
                timeseriesMatPurgeRequest{i}{I}.(A{J}).signals.values = timeseriesMat.drives{i}.(A{J}).signals.values(PurgeRequestIdx{i}(PurgeRequestStartIdx{i}(I)):PurgeRequestIdx{i}(PurgeRequestEndIdx{i}(I)));
                timeseriesMatPurgeRequest{i}{I}.(A{J}).time = [0; cumsum(diff(timeseriesMat.drives{i}.(A{J}).time(PurgeRequestIdx{i}(PurgeRequestStartIdx{i}(I)):PurgeRequestIdx{i}(PurgeRequestEndIdx{i}(I)))))];
            end

[Walter Roberson]

What happens if one of the PurgeRequestStartIdx{i} is empty because there is nothing requested to be purged for that item ?