LPC2294 UART0 (interrupt driven) ARTXv2.0

Hi All,
I'm running ARTX kernel and I want to use UART0 to send some data.
When I call putchar() it sends the first char and system hangs. U0IIR
says interrupt pending (bit0=0) and this is THRE interrupt
(U0IIR=0xC2). Program does not executes after calling putchar().
Please help,
Here is the init, putchar and interrupt vector from serial.c (It was
originally for UART1 and I modified it to use UART0.)
/* INIT SERIAL*/

void serial_init (void) {
// PINSEL0 = 0x00050000; /* Enable RxD1 and TxD1
*/
PINSEL0 |= 0x00000005; /// UART0
U0FCR=0x01; ///Enable FIFOS and reset
U0LCR = 0x83; /// DLAB =1
U0DLL = 0x20; /// 115200 baud
U0DLM = 0x00;
U0LCR = 0x03; /// 8 bits, no Parity, 1 Stop
bit ve DLAB=0 yapılıyor */
U0IER = 0x03; /// Enable RDA and THRE
interrupts */
VICVectAddr14 = (U32)int_serial; /// 14th vector is serial interrupt
VICVectCntl14 = 0x27; /// enable vect14 and assign IRQ number 7
VICIntEnable |= 0x80; /// IRQ 7 enable
sendstop = 0; /* CtrlQ not received
*/
ridx = widx = 0; /* clear buffer indexes
*/
}

/*---------------*/
/*-------Interrupt Vector--------*/

/*------
I have commented receive side but I read U0IIR to clear reset

---------*/
void int_serial (void) __irq {
U8 c;
c=U0IIR; ///for test only. will be deleted later
/*
if ((U0IIR & 0x0E) == 0x04) { /// Receive interrupt . Clears
flags
c = (char) U0RBR; /// read character

switch (c) { /// process character

case CTRL_S:
sendstop = 1; /// if Control+S stop
transmission
goto ack;

case CTRL_Q:
if (sendstop) { /// if Control+Q start
transmission
sendstop = 0;
} break;

default: /// send character to a mailbox

recbuf[widx++] = c;
isr_evt_set (0x0100, rd_task);/// set event character received

goto ack;
}

}
*/ /// Transmit interrupt

isr_evt_set (0x0100, wr_task); /// Go on, set event transmit
ready

//ack:
VICVectAddr = 0; /// Acknowledge Interrupt

}

/*-------PUTCHAR--------*/

int putchar (int c) {
wr_task = os_tsk_self (); /* identify task for serial
interrupt */
os_evt_clr (0x0100, wr_task);
/*
if (c == '\n') { /// expand new line character:
U0THR = (char)'\r';
os_evt_wait_or (0x0100, 0xfffe); /// wait till character transmited
} */
U0THR = (char)c; /// transmit a character
U0THR = (char)c; /// transmit a character

os_evt_wait_or (0x0100, 0xfffe); /// wait till character transmited
return (c); /// return character: ANSI
requirement
}