try DateTime.TryParse instead of Convert. though it should work anyway, try a specific culture, maybe try to specifiy an advanced format yourself and try invariant culture, too. same with styles.
dateString = "03/01/2009 10:00 AM";
culture = CultureInfo.CreateSpecificCulture("en-US");
styles = DateTimeStyles.None;
if (DateTime.TryParse(dateString, culture, styles, out dateResult))
Console.WriteLine("{0} converted to {1} {2}.",
dateString, dateResult, dateResult.Kind);
else
Console.WriteLine("Unable to convert {0} to a date and time.",
dateString);