Datetime ParseExact not working

Hi,

I want to convert the datetime from one format to other one..

Below is my code..

	inputFormat = "yyyy'-'mm'-'dd hh':'mm':'ss':'fffffff";	

string inputDateString="2012-12-19 04:03:20:0123456";	

	DateTime.ParseExact(inputDateString, inputFormat, System.Globalization.CultureInfo.InvariantCulture).ToString(ouputFormat);	
	
		

But this throws formatexception. Waht is wrong?