RTX RTOS TWO TASKS NOT WORKING SIMULTANEOUSLY

Hi, i am trying to implement two tasks in RTX RTOS.Purpose of the tasks are:
Task 1 waits for the pin15 of PORT0 to go high; if it does, then LED blinks.
Task 2 blinks LED irrespective of completion of task1.
But when I simulate the code, if I make the pin15 of PORT0 high, then both the tasks are running. If i "switch off" the pin15, then task 2 goes into ready phase and task 1 goes into running phase. I can't see the task2 LED blinking while the pin15 of port0 "switched off" . Please help.

this is the following code:

#include <rtl.h>
#include <LPC21xx.H>

OS_TID TID1;
OS_TID TID2;
__task void task1 (void);
__task void task2 (void);

__task void task1 (void) {
for (;;)
{

if(IOPIN0&(0x00008000))
{

IOSET1=0x00000001;
os_dly_wait (5);
IOCLR1=0x00000001;
os_dly_wait (5);

}

}

}

__task void task2 (void) {
for (;;) {

IOSET1=0x00000002;
os_dly_wait (5);
IOCLR1=0x00000002;
os_dly_wait (5);

}

}

__task void init (void) {
TID1=os_tsk_create (task1, 1);
TID2=os_tsk_create (task2, 1);
os_tsk_delete_self();
}

int main (void) {
IODIR1=0x000000FF;
IODIR0=0x00000000;
os_sys_init(init); /* Start the init task */
}