Need help to read in the Combobox into the "if elseif and else" function

I'm very new to PS so I got a Question:

I want to create a PS Script where I can select a name in a Combobox and then it should select the name in the if elseif and else. At the moment im not able to read the combobox and it only shows me the message from the "else" function.

I'm glad for any help.

Here is what I have at the moment:

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