Problem setting registry keys with windows installer in visual studio

Question

I'm trying to make a windows-installer project that installs a windows-service. During the installation, I want the user to enter an SQL-connectionstring in a textbox.

I want the connectionstring to be saved in the registry so that the service can later use it.

I found a lot of examples online that i tried to follow but i can never get it to work properly for me.

I have 2 problems:

1: I can make a new key in "HKEY_CURRENT_USER" but not in "HKEY_LOCAL_MACHINE"

When i define the key in "HKEY_CURRENT_USER", the key is made as expected (manufacturer is "MyCompany")

Configuration + result

When i ctrl+X the key and paste it into "HKEY_LOCAL_MACHINE", the key won't show up in the registry.

Configuration

Do i need to do something else before I'm allowed to set a new key in "HKEY_LOCAL_MACHINE" or am i missing something else?

2: The string in the textbox isn't written to the registry

Below, i have 2 screenshots of how i configured the registry and user interfaces. I named the Edit-proporty of the textbox "P1" which I also use as the value of "ConnString". From what I understand, this should make it so that the user-input gets written to the registry, however, the registry-value will be literally "P1".

Config. Registry

Config. User Interface

I have tried dozens of different configurations, I just can't seem to make it work.

If you need more info or screenshots from me, please let me know. Thanks in advance!