jQuery - datepicker.parseDate on 'mm/y' causing Invalid Date -

i have validate method seems pretty simple because use similar when using format mm/dd/yy, when use mm/y...i keep getting invalid date.

here validation:

function validatedate(datefield) {     try{         $.datepicker.parsedate('mm/y', datefield, null);     }     catch(error){         alert(error);     } } 

if pass in date 05/11...this logic complains date invalid. if change format mm/dd/yy , enter 05/11/2011...then says valid.

am missing when trying validate mm/y pattern?

unfortunately, need supply @ least month , day datepicker parse date properly. if leave year out, defaults current year, parsing "06/15" "dd/mm" give 2011-06-15. if either month or day omitted, default -1 , produce invalid date.

edit:

if trying confirm user entered valid month , year, this:

$.datepicker.parsedate('dd/mm/y', "01/" + datefield, null);