Running MCP23017 via I2C on ESP-01

Hello Forum,

I'm having trouble getting the MCP23017 to work with my ESP-01 running Espruino v87.

I'm using D2 for data and D0 for clock. This is the code I'm using to set up the connection:

I2C1.setup({scl:D2, sda:D0});
mcp = require("MCP23017").connect(I2C1, null, 0x20);

If I try to send commands to the MCP, e.g. "mcp.A0.mode("output")" I get the "I2CWrite: No ACK" error. I searched the forum and google to find a solution. I tried to use Nodemcu.D2 e.g. instead of D2, changed the frequency to 80MHz of the ESP, but nothing seems to work.

The wiring should be fine too, I have some C-Code doing some things with the MCP and that one worked, at least i could turn the ports of the MCP on and off. I've also added the 10K resistors on both pins, even though it was working without too, but that didn't help either...

The only thing I didn't try yet is connecting the reset pin. Everything's already soldered up and it's kinda difficult to change that now. But I tried removing the MCP and putting it back on, it's not directly soldered...

The address should be fine too, used it in the C-Code as well and "I2C.find(I2C1)" gives me Undefined...

Do you have any suggestions what I'm doing wrong here?