Compiler Error: Multiple channel write sites.

Hi,

My code as follows:

#ifndef SIMD_WORK_ITEMS

#define SIMD_WORK_ITEMS 4 // default value

#endif

#pragma OPENCL_EXTENSION cl_altera_channels : enable

// Channel declarations

channel int DATA __attribute__((depth(8)));

__kernel

__attribute((reqd_work_group_size(BLOCK_SIZE,BLOCK_SIZE,1)))

__attribute((num_simd_work_items(SIMD_WORK_ITEMS)))

void matrixMult( __global int *restrict A, __global int *restrict B)

{

// Write result to channel

int off = get_global_id(1) * get_global_size(0) + get_global_id(0);

int running_sum = A[off] * B[off];

write_channel_altera(DATA, running_sum);

}

__kernel

void FindMinAndMax(int size, __global int *restrict data)

{

int min_temp = 0;

int max_temp = 0;

for (int i = 0; i < size; i++) {

int val = read_channel_altera(DATA);

min_temp = min(min_temp, val);

max_temp = max(max_temp, val);

data[i] = val;

}

}

When I compile the kernels with command "aoc device/matrix_mult_bak.cl -o bin/matrix_mult_bak.aocx --report -v", it print out errors

"Compiler Error: Multiple channel write sites.". What the error means?How to solve the problem?Thank you!