Based on the error, I think probably you don't have snmpwalk installed; or maybe it cannot be run by you as you are currently logged in, or possibly the installation is incomplete or otherwise fubar.
First be sure the exe exists, then that you can run it from the command line. If it doesn't exist, your problem is obvious. If you just cannot run it, check the snmpwalk web pages for help about authorization.
I Developed application in C# with crystal reports and created setup file in third party (Advance) Installer.When i installed my application on client system application is working but ...