Help!!, G-code, Am I missing Something?

Hello, I recently picked up an Ender 3 and am confused about how it is interpreting a small program I wrote. The program is supposed to be a square with each side being 100 mm long.The script is as follows:G92 E0 G28G1 Z.750 F2000G1 X100.0 Y100.0 F3000G1 X100.0 Y200.0G1 X200.0 Y200.0G1 X200.0 Y100.0G1 X100.0 Y100.0 The issue that I am having is that the final line of the code is not being read, the extruder won't proceed to (100.0, 100.0) but proceeds to (100.0, 200.0) instead. I'm not sure what I am missing here. I am new to g code specific to 3D printing and am a not sure where to research syntax. I'm not sure if g code related to 3D printing is standardized so some info as to where I should start looking would be awesome. Thanks