Robotic Process Automation (RPA)

Hi I'm a newbie regarding RPA, just currently looking for tutorials and this is something that I saw in the samples in moving between windows, I keep getting the error "Parameter 'window' missing on command at line 5", does anybody know how to resolve this? 

Here's my sample script

defVar --name CalculatorWindow --type Window
defVar --name NotepadWindow --type Window
launchWindow --executablepath "C:\\Windows\\System32\\calc.exe" --safesearch  CalculatorWindow=value
launchWindow --executablepath "C:\\Windows\\notepad.exe" --safesearch  NotepadWindow=value
attachWindow --window ${CalculatorWindow}
click --selector "IdAndName" --controlsimilarity 100 --id num6Button --name Six
closeWindow --window ${CalculatorWindow}
closeWindow --window ${NotepadWindow}

Thanks