It has been a while that I'm away from programming for some reason. Recently I installed Qt 5.9 and went for re-doing my previous task which was an app.
I'd written that app purely in C++ and using Qt Installer Framework, I'd created an installable program. It worked well at the time but now nothing.

I have some folders:
config
packages
com.vendor.product
meta and etc

In meta I have three files named:
installscript.qs (shows only 0 and 1)
license.txt (shows nothing, blank)
package.xml (blank)

While all three have sizes.

What is the problem please? And how to solve it?