When You Encounter Problems in Istar

Link doesn't move with its Box

24 November 1997 We had a funny one. A box had a two links attached to it on the diagram, one to its left and another to its right. But when we moved the box around with the mouse, only the left link seemed attached to it. It appeared as though the box had only its left link. Yet the right hand link would snap to its new position once we moved the box to its new place and let the mouse button go. And when we clicked on the link its details panel came up, showing it to be an inference relationship from the attribute expressed by the box we had moved.

Reason: We had two relationships from the box to its consequent, not just one. As we could see when we brought up the attribute details panel of the box: it had two consequents, both the same. What was happening was that the two links each had a (complement-mode) sketchpiece when being moved around, which meant that the result was to draw the moving line in the original colours - hence invisible.

Solution: Remove one of the relationships via the relationship details panel. Or, if we need both links, bend one out of the way of the other.

Box outline is invisible

24 November 1997 Some boxes in an old KB had text but, seemingly, no box. The box outline was invisible. When we moved the box there seemed to be a glimmer where it moved, but the box was invisible.

Reason: The box pen number had exactly the same colour as the background.

Another possible reason: The box pen number is 0, that is the background pen.

Solution: Alter box pen number via attribute details panel, or alter the colour for this pen number via the Easel panel.

Attribute Action Panel doesn't show Infer Button

6 February 1999 I was stumped! I had an attribute attached to a Form (attribute 1Bayesian in the form knowledge base in TestKBs), but when I clicked on it with left mouse button, its attribute action panel showed only a Reset Button and no Infer Button. (It showed Data, Delete, AddGoal and Done buttons OK.)

Reason: The attribute had become Overridden. When I brought up its Attribute Details Panel, the Override gadget was checked. (Note that the CanOverride gadget was blank - this was because it had probably become overridden via an Override Form.)

Remedy:

  1. Bring up Attribute Details Panel, check the CanOverride gadget, and hit OK.
  2. Bring up its Attribute Action Panel. Now there should be an Override Button.
  3. Hit the Override Button on Action Panel. You should be asked a Question for the attribute, and on the Question Panel there should be an Unset Button.
  4. Hit the Unset Button.
  5. Now try the Attribute Action Panel, and the Infer Button should be present.
  6. Might also have an Override Button below it; this can be removed on the Attribute Details Panel by clearing the CanOverride gadget.
    Copyright (c) Andrew Basden 1997.