Datepicker does not allow manual entry of alphabetic characters

I am using the datepicker plugin with dateFormat: 'dd-M-y'

When I try to manually type a date into the field, it is ignoring all alphabetic input (except for 'M' and 'y' strangely). This makes it impossible to fill in my month abbreviation.

I think a user should be allowed to manually type in the date if they choose to, and this should work even when dateformat involves full or abbreviated month names.

My full defaults are:

{

dateFormat: 'dd-M-y',

showOn: 'both',

buttonImageOnly: true,

buttonText: 'Click Here to Pick the date',

buttonImage: '/images/cal.gif',

speed: 'fast'

}