Need help in incrementing the date in oracle

Error thrown as "Invalid number" while trying to increment the date. Given below is the query executed through sqlplus. Please help me on this.

select ''''||to_date(:To_date, 'dd-mon-yyyy')+1||'''' from DUAL;

Expected output:(if :To_date variable is '09-DEC-2014')

'10-DEC-2014'