Hi,
The pick query option is useful when you have some coincident entities (nodes, elements, curves, surfaces...).
For example, if you want to list one of two coincident nodes, first activate Pick Query option, then List / Model / Node. Click on one node and a little window will appears with both nodes IDs to allow you choosing the one you want then click OK.
Even if there is only one node and you activate the pick query option you should be able to select the node.
Hope this helps,
Seifeddine Naffoussi, Stress Engineer