Hi,
Can you check the view
CRMCMP_IC_FRAME/HiddenView component CRMCMP_IC_FRAME to check END button functionality.In this view put the break point in event
EH_ONFORWARDCALL and check it.
Need to check about back button try to use this standard class : CL_BSP_WD_HIST_MANAGER_BASE , method ON_HISTORY_TRIGGER.
Regards,
Sumeet