I'm new in OOP with PHP and I'm wondering why I can't declare an instance variable in my class so that I can use it properly. If declaring the variable like on the picture at the top, I get the error message from picture 3. If I add the "public" modifier to the variable, my PHP file says exactly nothing (No Error, just a white empty screen). It all works when I write the string directly into my function, but I wanted to try out using an instance variable.
I tried to solve this problem by myself and didn't find any solutions. So please don't be too mad about it.