LPC2378 serial interrupt problem

LPC2378 serial interrupt problem
following code is working fine in interrupt for UART0

        InitUART0();
        U0IER   =0x04;
        while (1)
        {
                U0IER   =0x0F;
                if(buff1[0]=='c')
                {

                        TransmitChar0('I');TransmitChar0('N');TransmitChar0('D');
                        TransmitChar0('I');TransmitChar0('A');
                        clear_Rxbuffer();
                }

                else  if(buff1[0]=='d')
                {
                        TransmitChar0('W');TransmitChar0('E');TransmitChar0('L');
                        clear_Rxbuffer();
                }

                U0IER   =0x00;
       }

also UART1 in interrupt working individually fine in code
I want to use UART1 and UART2 both simultaniously but only one uart communicatio so far done
please suggest how to use both interrupt simulataniously

Thanks in advance
Kishor P.