Return error message from custom action to web setup installer

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C#

Hi,

I want to return a error message to web setup installer from custom action (my custom action is windows form). How to pass the value to installer from window form?
Now I am using the following code,

from Installer I am overriding the Install method

public override void Install(IDictionary stateSaver)
        {
            try
            {
                base.Install(stateSaver);
            }
            catch(Exception ex)
            {
               throw new InstallException("error");
            }
        }

In windows form,

throw new InstallException("error");

This is working fine in form constrctor when first custom action form is calling from installer. But it will not return a value to installer from an Event. So how to do?