[Kanegasi]

That's the issue. The local variable is nil. It needs to be a table before you assign any indexes.

You also need to create a separate frame for each button, but that top line in the loop will reuse the same frame over and over again, only creating one button that will either keep moving over 5 pixels or error trying to create a second button because you can't anchor a frame to itself.

Change these two lines:

local mapButton;
mapButton[i]=DragExample or CreateFrame("Button", "DragExample", UIParent, "ActionButtonTemplate,SecureActionButtonTemplate,SecureHandlerDragTemplate")

To these:

local mapButton = {};
mapButton[i]=CreateFrame("Button", "DragExample" .. i, UIParent, "ActionButtonTemplate,SecureActionButtonTemplate,SecureHandlerDragTemplate")

This makes mapButton an empty table, ready to accept the indexes you're trying to assign, and properly creates a separate frame for each button with the index appended to the global name so they can all coexist.