Thankful for any input.
Hello @SIAH and welcome…it looks as you feed in line in your startpoint in your linebystartandendpoint…that node expect points…
How is it possible to go around the problem? I though while i extract the points coordinates with Getitematindex node I would be able to connect them. Thanks
Yes…try to look at @Alban_de_Chasteigner page he had some nice exemple how it could be done 
but as far i can see it isnt the right index as you get lines but need points 
Amigo @SIAH hola, I’m agree whit @sovitek, I also advise you to train yourself a little more in the basics of Dynamo so you can understand it better before venturing into more complicated workflows, take a look at the hand book I leave you the link, also I leave you a workflow to decompose curves, I hope you find it useful.
