Why does Photon Instantiate only work with a direct input name but not a variable?

Hello!

I'm trying to instantiate an object by using a variable which contains a string of the item you're currently holding. The string in the variable is the exact same as the prefab name but once i try it out in the build version (in the unity editor it works fine) it returns an error (see image). The prefab is 100% in the Resources folder. When I remove the variable and only instantiate with just the name in the instantiate node it works! But once i connect the variable to get the string it stops working.

the second picture shows the script when it works but it's not what i need because you need to be able to instantiate different items not just one. When i connect the variable (right next to the instantiate node) it stops working even though the name is still the same. Even using " string literal" gives me the errors!

Does anyone know why it wont work with a variable or any other node???