why do my checkboxes only bring back the correct data if i select them checkboxes in order from first to last?

I've got some checkboxes attached to my table. if you select one it brings back data the be used for serval function. but the correct information only comes back only if I'm selecting checkboxes from top to bottom, for example, if I selected one from the middle and then selected the one above it returns a duplicate of the first. but if i select the first and any below it it works. I don't get what could cause this. checkboxes code for checkboxes