Arduino Serial Port. COM1 does not exist
Never used Visual Basic but:


There is no such thing as Serial1 on Arduino Uno. There is only Serial. (Serial1, 2, 3 are available on ArduinoMega) Reference: Arduino
For COM port you should check your device manager. Often it appears at COM3 so probably you should check this issue.


Just for curiosity: Why VB? Is it only your choice or it use less ram or memory, works faster or anything?