Trouble with custom data tip function (event)

I am puzzled? I try to have a line drawn during the call to a custom text data tip function.

Here is the "normal" response, when clicking on a point with the mouse :

Here's the error message I get when I try to do the same mouse click while adding a few extra lines of code in the callback (first, a screen capture of the message, followed by the code :

Here is the code :

function txt = displayCoordinates(~, info)

global clickedCIE_L clickedCIE_a clickedCIE_b; % sorry for the globals abuse...

clickedCIE_L = info.Position(3); % 69

clickedCIE_a = info.Position(1); % -56

clickedCIE_b = info.Position(2); % 46

% handle_ligne = line([0 0],[clickedCIE_a clickedCIE_b],[0 0],'color',[0 0 1],'lineWidth',4);

DisplayAngle(clickedCIE_a, clickedCIE_b); <<< --------------------- This statement is causing the error?

Hrad = mod(atan2(clickedCIE_b,clickedCIE_a),2*pi); % 2.4539

hueAngle = Hrad*180/pi; % 140 degrés

chroma = sqrt(clickedCIE_a.^2 + clickedCIE_b.^2); % 72

txt = {sprintf('CIE L: %.0f', info.Position(3)), sprintf('CIE a: %.0f', info.Position(1)), sprintf('CIE b: %.0f', info.Position(2)), sprintf('CIE c : %.0f ', chroma), sprintf('CIE h : %.0f °', hueAngle) };

end

function DisplayAngle(a,b)

global clickedCIE_L clickedCIE_a clickedCIE_b;

a_start = 0;

b_start = 0;

a_end = clickedCIE_a

b_end = clickedCIE_b

% Delete existing marker, if any

if ~isempty(handle_ligne)

delete(handle_ligne);

end

handle_ligne = line([a_start a_end],[b_start b_end],[0 0],'color',[0.2 0.2 0.2],'lineWidth',4);

end

It does not matter whether I put the DisplayAngle function inline of not, I still get the error message.

Would there be any other approaches? All I'm trying to add to the figure is a line depicting the hue angle and chroma, at the bottom.

I'll continue looking around for the error on my own in case I find any solution... And I appreciate your precious help.