It doesn't work because you have white spaces in your text file. You have to use trim to eliminate them and if your search isn't case sensitive I would also use lowercase.
That should now work:
+ System: On start of layout
-> Array: Set size to (0, 1, 1)
-> AJAX: Request mproduct.txt (tag "produkt")
+ AJAX: On "produkt" completed
----+ System: For "" from 0 to tokencount(AJAX.LastData,";")-2
-----> Array: Push back lowercase(trim(tokenat(AJAX.LastData,LoopIndex,";"))) on X axis
+ TextBox: On text changed
-> Text: Set text to TextBox.Text
+ Button: On clicked
----+ Array: Contains value lowercase(trim(Text.Text))
-----> Text: Set text to "found"
Image Upload doesn't work.