Sorry I cannot answer this, but you are not alone.
I'm having the same difficulty. I have a script called start_script located in my home directory (/home/tony) that looks like this:
At the terminal I can type in the name of the above script and it launches the start_program (which is a tcl/tk program) just wonderfully.
I right clicked on my desktop and chose "Create Launcher". In the "command" line I entered:
... and in the "type" I first chose "application" but have also fiddled around with other settings for this - including the "link" selection.
I click on my shiny new icon .... nothing happens.
Can someon please help with this?