Ruby Shoes execute another ruby program

I've got a small shoes (3.3.3) program and a small ruby console program with selenium (3.4.4). If I open the selenium console program directly everything works fine, but if I want to open it via "exec("")" through shoes, it breaks and closes.

I thought the error is the webdriver, so I've written a simple console program with some easy "puts" output and shoes displays the console and the output.

The thing is... the selenium program worked yesterday and I can't find the problem, why it doesn't now.

The simplified shoes code looks like this:

Shoes.app(width: 200, height: 200, resizable: false){
    button("GO", width: 200) do
        exec('ruby data/test.rb')
    end 
}

Here comes the simple selenium-webdriver code named "test.rb":

require 'selenium-webdriver'

Selenium::WebDriver::PhantomJS.driver_path = 
"driver/phantomjs/bin/phantomjs.exe"
browser = Selenium::WebDriver.for :phantomjs
wait = Selenium::WebDriver::Wait.new(:timeout => 15)

browser.navigate.to 
"http://www.accuweather.com/de/de/heinsberg/52525/weather-forecast/174475"

wetterElement = browser.find_element(:id, "wrap-forecast-feed")
@wetterData = wetterElement.text.gsub(/\n/, ',').split(",")
puts @wetterData[1]

gets.chomp

Shoes gives me the following error message for a few msecs before it breaks:

So I looked it up, and found this code snippet:

  def assert_file(path)
    return if File.file? path
    raise Error::WebDriverError, "not a file: #{path.inspect}"
  end

  def assert_executable(path)
    assert_file(path)

    return if File.executable? path
    raise Error::WebDriverError, "not executable: #{path.inspect}"
  end

I really have no idea... Thank you in advance.

Got it ... The folder with the shoes app was UTF-8 formatted. Simply changed the name and it worked.