asp.net - Converting Date string to DateTime Format vb.net -

i have example , gives me exception "conversion string x datetime invalid"

here method validate datetime.

example date string : "27/03/1985"

public function validatedatecolumn(byref fieldname string) boolean      try         if isdate(fieldname)             dim actualdate datetime = cdate(fieldname)             dim dtlicexp datetime = cdate(actualdate.tostring("d", thread.currentthread.currentculture))             fieldname = dtlicexp.tostring("mm/dd/yyyy")             return true         end if     catch ex exception         'fieldname &= "format must mm/dd/yyyy"         return false     end try  end function 

any idea validate date string formate datetime.

i want convert date "27/03/1985" datetime.

i'm using asp.net vb.net.

have @ using datetime.tryparseexact method or datetime.parseexact method