Ic2, connect lcd and sensor

Like to connect 3 x ic2 temperature sensors and one ic2 LCD to my Arduino. The lcd works and the sensor works but when i connect the sensor and the LCD at the same time, nothing works anymore. I know that pull-upp resistors are supposed to be used but as long as i connect only one device it works perfect. Any suggestions?

Probably an address conflict, I2C devices have a particular address so you can have multiple devices on the same pair of wires (bus), you could use an I2C scanner program to discover the addresses of each device (one at a time). http://playground.arduino.cc/Main/I2cScanner