Application Error

When I was using HyperView to see my result.

Some times it will show

can't read 'Priv(where)': no such element in array
can't read 'Priv(where)': no such element in array
    while executing
'if {$id(where) eq 'item' && $Priv(where) eq $id(where) && $Priv(item) eq $id(item)} {
        ProcessSelection $W $x $y
    }'
    (object '::post::pa::_hvpaobjpo_viewmodel' method '::hwtk::pa::Area::OnLMBRelease' body line 3)
    invoked from within
'::post::pa::_hvpaobjpo_viewmodel OnLMBRelease .post_results.model.f2.hvpapo_viewmodel.ftree.tree 342 119'
    (command bound to event)

What is the problem of my software.

Because I also can see my h3d in HyperView and it is normal to see result.