Create a new figure when using ButtonDownFcn

This is a follow up to my previous question: https://www.mathworks.com/matlabcentral/answers/409465-use-buttondownfcn-on-an-image

I was able to get the 'CurrentPoint' property of the axes of the figure I want to analyze. I then take the contents of CurrentPoint entries (1,1) and (1,2) (b/c my plot is 2d), convert them into "entry numbers", and use these numbers to reference the corresponding data entry in a data array in my possession. Now, I would like to plot the contents of that data entry, as well as the result of a mathematical function acting on those data values, each in their own figure. I had created 2 figures with titles, labels, etc within the function that I had intended to use as the ButtonDown function callback. My question is, how do I invoke the ButtonDownFcn now? I tried plot('ButtonDownFcn',@myfxn), but the result is:

    Error using plot
    Invalid first data argument.

Thanks in advance.