Converting time to Military
Instead of formatting the string manually, you should use:
oos.ToString("M/d/yyyy HH:mm");
Also, what do you mean by "would not accept a value"? Are you getting an exception? If so, what is the error message?
Beside first answer check this:
http://msdn.microsoft.com/en-us/library/az4se3k1.aspx
http://msdn.microsoft.com/en-us/library/8kb3ddd4.aspx