How to run a VB.NET exe in the backend on Azure VM server?

I have an azure VM running as a server for my site. The site launches another VB.NET process in the backend which creates an excel and performs some formulas on them. The exe when double clicked and run on the VM works fine so there seems to be no environmental or installation issue. But when launched from the site I see that the process starts and the excel file is created, the task manager shows the process is running but it seems to go on a halt state. The exe doesn't perform any formulas and calculation that it had to do on the excel after creation. And it doesn't give any error either. The front end site just keeps waiting.

The code for launching the process is as follows.

  var proc = new Process
        {
                StartInfo = new ProcessStartInfo("App.exe")
        };
        proc.Start();
        proc.WaitForExit(); 

I don't think its a permission or rights issue as the exe does launch and start. I have given my IIS AppPool the rights to the folder as well.