Hello. I am trying to use a SWITCH statement that uploads a specific ECG data based on the selected string of a Pop-Up menu. This data should then be visualized in the Axes Box of the GUI. When I start running the GUI, the initial data is uploaded without any problems, but once I choose another string from the Pop-Up menu, it displays the error "SWITCH expression must be a scalar or a character vector." How do I fix this? I have uploaded photos of the Opening Function, plot function, and Pop-Up menu callback functions so you can better visualize the problem.