OLE no ClassFactory registered

I am maintaing an ruby-application. The ruby installation is packaged into a ThinApp. The Ruby Code is located on a network-share. Now there is a Problem with OLE and excel.

This is a sample code that produces the error.

require 'win32ole'

puts 'Starting Test'
excel = WIN32OLE.new('excel.application')

Traslated error message:

test.rb:4:in initialize: failed to create WIN32OLE object from `excel.application' (WIN32OLERuntimeError)  
    HRESULT error code:0x800401fe  
      Applicaiton has been started, but there is no ClassFactory registered.  
        from Z:/ruby test/test.rb:4:in `new'  
        from Z:/ruby test/test.rb:4:in `<main>'  

If I try WIN32OLE.new('word.application') my code works without an error.
Also WIN32OLE.connect('excel.application') works if excel is already started.

Has someone an idea what is cause of this problem?

Thx for your help