Why doesn't my Karabiner modification show up in the Add rule sheet?

I made this complex modification for Karabiner

{
	"title": "change_to_qwerty",
	"rules": [
    	{
	    	"description": "Change input source to QWERTY while left_command is held down.",
			"manipulators": [
				{
					"type": "basic",
					"from": [ 
						{ 
							"key_code": "left_command",
						}
					],
					"to": [
			    		{
			    			"key_code": "left_command",
							"select_input_source": {
								"input_source_id": "com.apple.keylayout.US"
				  			}
						}
			  		],
			  		"to_after_key_up": [
						{
							"key_code": "left_command",
				  			"select_input_source": {
								"input_source_id": "com.apple.keyboardlayout.Programmer Dvorak$"
				  			}
			    		}
			  		]
				}
	  		]
    	}
    	{}
  	]
}

and put it into ~/.config/karabiner/assets/complex_modifications but it doesn't show up. I thought maybe it's because the file has errors but I can't find one. Please someone tell me how I can make the modification show up in the "Add rule" window