I have same problem but i solved by using IFormatProvider
Dim provider as IFormatProvider
provider = new system.globalization.cultureinfo("en-GB",true)
dim future as system.datetime
dim Mystring as string
mystring=txtdate.text
dim mydatetime as datetime
mydatetime = new datetime()
mydatetime=date.parse(mystring,provider,system.globalization.datetimestyles.nocurrentdatedefault)