We have a problem using the jumpers. We’ve downloaded the example posted here but we get an error message in the output window: “Error : 1” and we don’t know how to fix it.
We have the print screens:
and 
You are getting a linking error. You need to make sure that you have declared (written) all the functions you used. Do a careful scan of the entire source.
If you can’t find it, post the source here as an attachment.