.net - Date format with AM/PM designator is not correctly parse -

i'm using code convert string date.

dim outputdate date ' have tried datetime dim inputstringdate string = "january 14, 2013 pm" dim dateformat string = "mmmm dd, yyyy tt"       isvaliddate = date.tryparseexact(inputstringdate, dateformat, new cultureinfo("en-us"), _                                       globalization.datetimestyles.none, outputdate)     ' isvaliddate = true outputdate.tostring(dateformat) 'january 14, 2013 

the issue "tt" not recognize. input text "pm" (january 14, 2013 pm) after parsing date , applying format got "am" (january 14, 2013 am).

the time of outputdate 00:00:00, think should pm default time 12:00:00.

environment: .net 2.0
dtinfo.pmdesignator = pm
dtinfo.amdesignator = am

thanks help

overview

when trying parse date string am/pm designator (tt) without time (hh:mm), example “january 14, 2013 pm” (mmmm dd, yyyy tt), seems .net framework 2 successful parse ignore am/pm portion setting time default, midnight (00:00). solution giving time e.g. “hh:mm tt” or “hh:mm”.
using .net framework 4 in same scenario, parsing date string without time fail; because .net 4 require time , am/pm designator (hh:mm tt), or use of 24 format (hh:mm). @dave michener (please review comment)

so in .net 4
mmmm dd, yyyy tt --> fails
mmmm dd, yyyy hh:mm --> fails
mmmm dd, yyyy hh:mm tt --> works
mmmm dd, yyyy hh:mm --> works

correct me if i'm wrong there's no such thing 'pm default time'. there's default time value if don't specify time @ ("00:00:00"), if don't specify minutes , seconds ("hh:00:00") or if don't specify seconds ("hh:mm:00"). if want pm need give time work with. wouldn't know talking if fed "am" input either, happens default uses when understands format can't unambiguously parse time looks understands.