tcp/ip connection thingspeak

Hi. Im using sim800 for sending data to thingspeak channels when connecting to api.thingspeak.com with port 80 everything is ok. But after sending" update?api_key=YYP2Q3T8UZ2WBP6H&field1=0 " by sim800 it closes the connection and 400 Bad Request error appears on the debug session. I tried this with hercules serial terminaal and same results .