[Qgis-user] Problems with v.net.iso

[Laurens Bakker]

Hi everyone,

I'm trying to determine a service area using the v.net.iso grass tool.
This is the tutorial i'm using:
http://gracilis.carleton.ca/CUOSGwiki/index.php/Using_GIS_for_Decision_Support_in_Emergency_Medical_Services
Everything goes fine until I get to the point of "create servie areas" 
step 3 (all steps before that have been executed without problems). Once 
I try to set up the tool i can't select anything from the dropdown menu 
at "input nodes", meaning I can't execute the tool. Any ideas on why I 
can't select my input nodes?

Thanks,
Laurens