one led or more than one led to one pin always work, but whenever i try to connect another led to another pin(i.e 12). the light emitting by the led is so little. here is the image.
Maybe you could post a schematic and some code?
Maybe this will help? http://www.arduino.cc/en/Tutorial/DigitalPins (especially in the "Pull up resistors" part).
especially in the "Pull up resistors" part).
He's trying to output.
Yes, but we don't see his code, and:
Note that the pullup resistors provide enough current to dimly light an LED connected to a pin that has been configured as an input. If LED's in a project seem to be working, but very dimly, this is likely what is going on, and the programmer has forgotten to use pinMode() to set the pins to outputs.
Which seem to be exactly his problem 