C#时间格式转换的问题！

Question

/./第1个时间
string time1 = "20171001091256";
/./第2个时间
string time2 = "20181001161742";

想要把这种类型的字符串转换成时间：但是第一个可以转换，第二个就转换不了，出错！

DateTime dt = DateTime.ParseExact(time1, "yyyyMMddhhmmss", System.Globalization.CultureInfo.CurrentCulture);

转换正常！

DateTime dt = DateTime.ParseExact(time2, "yyyyMMddhhmmss", System.Globalization.CultureInfo.CurrentCulture);

转换出错！提示：String was not recognized as a valid DateTime.

请问各位大神问题出在哪里啊？