Hello. I have spent a long time searching but to little avail.

I'm new to a project that uses Shared Variable Nodes to pass data around. I have created a copy of the whole project and subvi's to work on without upsetting the original, which we need to keep operational.

In the copy I can't use any shared variable nodes. I can drag 'blank' ones off the pallet, but I cant double click and select which shared variable I want to assign to the node. If I right click the blank node and go to properties all the options are blanked out, so I can't choose a path to select a shared variable either.
If I use a VI with an existing shared variable from the original it works fine until I do 'anything' to the node, then it breaks the wires and displays a little red explanation mark.

I can modify/add/edit shared variable nodes in the original, just not the copy. Why is this? I have checked the licence manager and I can't see DSC in there - is this the problem? If so why can I work on the original unimpeded?

Thanks very much for your help.