Hi Andie,
Can you check the data rule assigned for this transaction,
SPRO->CRM->Basic functions->Date management->date profile. you can check here for the determination of date rule. I strongly believe that there is some date rule to determine the end date.
One more thing whatever input you are giving system is converting to todays date only? Try giving some future date in end date value.
Best Regards,
Dharmakasi.