Transmit 4 - Use the returned boolean

I need some help with the following script i made.

Everything works except the move to trash part at the end -I believe the part where i want to check if the upload has succeeded by passing the returned boolean to theUpload parameter is where my script is a bit off.

Please feel free to help me out here

set theServerAddress to "[url=ftp://ftp.iwanttouse.com]ftp.iwanttouse.com[/url]"
set theUserName to "username"
set thePassword to "password"
set theRemoteDirectory to "/home/hd1/folder1/subfolder1"
set theLocalDirectory to downloads folder
set theUpload to false as boolean

set this_item to choose file with prompt "Choose file:" default location the path to downloads folder


try
	-- Connecteren with the ftp server
	tell application "Transmit"
		tell current tab of (make new document at end)
			connect to address theServerAddress as user theUserName with password thePassword with initial path theRemoteDirectory with protocol SFTP
			
			-- Upload the File
			tell remote browser
				upload item at path this_item
				if boolean returned is true then
					set theUpload to true as boolean
				end if
			end tell
			-- Disconnect
			close remote browser
		end tell
		quit
	end tell
	
	-- Move the uploaded file to the trash
	if theUpload = true then
		tell application "Finder"
			move this_item to trash
		end tell
	end if
	
end try