"error performing subscript operation" on Perspective view text box bindings

In a Perspective View, many text boxes that all have a tag history binding to OPC tags, I'm getting 'null' displayed rather than valid values, and in the warning for the property, per the attached message it is Error_ExpressionEval("Error performing subscript operation").
I have a good connection to the PLC tags that these bindings are to, and the binding previews show ok, per the attached screen shot as well. Also, I can add a new text box and create the same kind of binding to the same tag(s) and it displays / works OK. So... , what might be going on here with this problem/error on the existing components, am I missing something obvious? Thanks much!

I suspect there's more to that binding than you're showing us.
Make that binding window taller and screenshot it again.

There you go, about as tall as I can get, thx.

Can you make a table and use that same binding on it, except without the expression ?

Yeah, here it is. I made sure that all details were the same, with historical vs realtime and the same date range. Let me know if that's wasn't what you were looking for. Thanks.

I'm... not sure where to look.

The Error_ExpressionEval("Error performing subscript operation error suggests that there's an issue when trying to retrieve data from the dataset with the subscript operator ([0,2]), but... I don't know what that issue would be.

One last shot: Try changing the return format of the query from dataset to document, and in the expression change {value[0,2]} to {value}[0]['durationOff'], see if that also throws an error.

  1. When I do your suggestion, changing it to 'Document', changing the format Transform, then I get null value returned, but not null outlined in red as if there is an error.

  2. Interesting find since my last reply when I was trying this! If I remove the tag path, then apply, OK to exit and save the project, and then go back into the binding, re-add the tag by browsing to it again and then apply, OK, exiting and save the project, it fixes it! The correct value then populates without error. I have a LOT of text boxes on the view to do this to, but it would fix it. So.., some kind of bug/corruption perhaps?

Thanks again Pascal for the help.

You might have had a similar situation if you did a refreshBinding on the bindings.