Read data from value, that is set by "setDataProperty"

Hello,

how i can read the vaule of attribute, when i set it with the method " setDataProperty ",
i try to read it by " findObject " but it isn’t working below is my script

thinLine.onclick = function() {
try{
diagram.startTransaction(‘thin Line Width’);
obj.diagram.model.setDataProperty(obj.part.data, ‘thickness’, “1”);
diagram.commitTransaction(‘thin Line Width’);
alert(obj.findObject(“thickness”).text);
} catch(ex) {
var place = "IPRO-CONTEXTMENU: thinLine.onclick → ";
ex.name = place + ex.name;
writeToLog(ex, 0, LOGLEVEL.ERROR);
}
}
// Visible thinLine for the relevant GraphMod and selected option
function visiblethinLine() {
return !isViewMode() && obj.part.findObject(“thickness”).text === “1” ? true : false;
}

obj.part.data.thickness

The reason you need to call Model.set or other Model methods in order to modify the state of model data, is that the model needs to know that a change has been made so that it can propagate a ChangedEvent to any interested listeners and evaluate any dependent Bindings, which in turn can result in performing layouts or other effects.