Unable to load dll file from installer class, during installation at register user dialog

[WomanPro]

Hello, I have created a solution at vb.net 2019 with 3 projects, the first project includes just a form to load, the second BackgammonRegistrationLicense includes an installer class, a dll file named foxlearn.license.dll and a registration form that genarates and register a serial key for the application that is going to be installed. The third project is a setup project in which I have included both primary outputs of the projects I mentioned above and simulteneously when adding primary output of BackgammonRegistrationLicense foxlearn.license.dll is being included too. Well, in the setup user interface I have 2 radio buttons for full license and trial and at register and a Register User dialog too with executable set to primary output of BackgammonRegistrationLicense. No errors, no warnings when I build the setup. But when I am trying to run the setup, I get an error when I press the register now button at register dialog which says: Unable to load foxlearn.license.dll in BackgammonRegistrationLicense. What am I missing over there? May somebody help me to correct it? Any help will be much appreciated. Thank you so much in advanced.