voltage sensor and LCD

Good Morning from Indonesia :slight_smile:

Sir, I have made a project voltage sensor based in this link http://openenergymonitor.org/emon/buildingblocks/measuring-voltage-with-an-acac-power-adapter

and i display it on a lcd . But when the sensed voltage connected , the display character on lcd are damaged or error . What troubleshooting should i do for this problem sir? Thanks before :slight_smile: