run nant build file in command prompt using c#

I have a build file with nant n开发者_如何转开发ow all I need to do is execute it with command prompt using c# I tried the below but I am not able to build it ..

System.Diagnostics.Process.Start("exe -buildfile:d:\buildfile.build);

and when I am running through cmd prompt directly it is working

Have you setup nant as an environment variable?

System.Diagnostics.Process.Start("nant.exe -buildfile:d:\buildfile.build);