the issue is likely the text format you have.
I believe that Crystal assumes it is MM/dd/yyyy fromat not dd/MM/yyyy format.
NOt sure about how it will handle the text>text but if you want to try it make your totext(date) force formating to be the same as your xml string.
It will be seomthing like the below but you may have to chnage as i do not know if you are showing lead zeros in your day and month fields (1/1/2009 or 01/01/2009)...
{DATETIME_IN} >= totext(currentdatetime,'d/M/yyyy hh:mm:ss')
Or if you convert your string to a date you have to swap out the month and date parts.