Hi Maria,
While creating the transaction code, have you selected the correct option? If this is an executable program, you need to select the second option " Program and selection screen" (report transaction).
You also need to specify the correct program name and screen number which needs to be executed by your tcode. Please check these details and let us know if you need any more help. You can also tick the SAP options for HTML, JAVA and Windows.
Hope this helps