Hi Sini-Kit
One problem is with this part:
yourMessage={{||3dsliderModal}}
Transcluded attributed are never wikified; the text is passed through directly, and so the double bar syntax is not used with transcluded attributes.
If I understand your goal correctly, you’ll need to pass the current tiddler explicitly to the modal:
<$action-sendmessage $message="tm-modal" $param="SampleModal" currentTiddler=<<currentTiddler>>/>
Then your modal can pick up the caption field and other values that you are displaying.
Best wishes
Jeremy
and so don’t need to resolve the value of the current tiddler.