★Why can't external reference drawings be bound in ZWCAD

Issue:

As shown in the figure, the Bind option is grayed out and unavailable when right-clicking the reference drawing. How can this be resolved?

Solution:

1. Click the menu Insert → External Reference (or execute the XREF command) to open the External References manager dialog box.
2. Click the Tree View button at the top right of the External References manager, as shown below.
   
3. Check for nested references. Nested references must be either Detached or Bound before the primary reference can be bound.