Why app designer does not set my modified DataTip in the plot? ERROR: UNABLE TO UPDATE

My code is:

fig1 = figure('Name', "Graph");
Graph = digraph(app.G', app.U, 'omitselfloops'); %G and U are matrix and column vector
H = plot(Graph, 'NodeCData', R, 'MarkerSize', R*500, 'EdgeColor', [0.8 0.8 0.8]);

datacursormode on;
hdt = datacursormode(fig1);
disp(hdt);
hdt.UpdateFcn = @(obj, event_obj) app.GraphCursorCall(obj, event_obj, app.OUT, app.IN);
set(hdt, 'UpdateFcn', [@hdt.UpdateFcn] );

Matlab does not detect errors, but property of DataCursorManagement is not set and i don't know why.

The function to use is:

function output_txt = GraphCursorCall(~, event_obj, out, in)
% Display data cursor position in a data tip
% obj          Currently not used
% event_obj    Handle to event object
% output_txt   Data tip text, returned as a character vector or a cell array of character vectors

pos = event_obj.Position;

 output_txt = {['AGO ' num2str(pos(1), [1:length(out)])], ['OUTDEGREE: ' num2str(pos(2),out)], ['INDEGREE: ' num2str(pos(3),in)]};
end

[Vincenzo Bianco]

I tried also:

set(hdt, 'UpdateFcn', @hdt.UpdateFcn );