hii....don´t know how you now connected the two devices that are IRON-BLUE ALUMINUM SPEAR - MZFAISF-3 (TELESCOPIC ROUND HEAD).
A popular mistake ist to connect tx with tx and rx with rx on both sides but you have to connect tx with rx and rx with tx. Also you need to have the same GND for both devices.
A popular mistake ist to connect tx with tx and rx with rx on both sides but you have to connect tx with rx and rx with tx. Also you need to have the same GND for both devices.