Using isDate return true vb.net -

when i'm using isdate() method in .net. returns invalid result. why "ad05ad09" read date. following code i'm using. please give me proper reason this

    dim value string     value = "ad05ad09"     if isdate(value)         dim odate date         odate = cdate(value)         msgbox(format(odate, "yyyy-mm-dd"))     else         msgbox("a")     end if 

as writtern in msdn:

isdate returns true if expression of date data type or can converted date; otherwise, returns false.

but should go common ways, datetime.parse, datetime.parseexact, convert.todatetime , more.

see msdn example:

dim datevalue date dim datestring string = "2/16/2008"   try   datevalue = date.parse(datestring)   console.writeline("'{0}' converted {1}.", datestring, datevalue) catch e formatexception   console.writeline("unable convert '{0}'.", datestring) end try