RS232 buffer voltage level

Hi,
On pin 2 of my MAX232 IC is about +6V and on pin 6 is about -6V. This situation changed when I add in other ICs on my circuit board. Now, on pin 2 of MAX232 IC is +6V and on pin 6 is about -4V. Since the stadard voltage level is +9/-9V, is the voltage values I get are still acceptable?

I mean this is some power supply probleme. When the MAX232 supply voltage is 5V, the voltages +10 and -10V, no changed when You connect properly another IC-s. So check the 5V supply.