Unable to invoke putty.exe from Teamcity using Nant

I am a newbie to Teamcity and was trying to build a database release script functionality as a final step to the build process. The release scripts are already in a ksh file and hence, i don't want to re-write it.

As such Teamcity is able to run the Nant program and do the build successfully, however, when I added the step to invoke putty.exe from the .build file, it just keeps on running.

Please can someone tell me a way to invoke a ksh script from Teamcity using Nant?