Opannotate the flag --search-dirs doesn't work

I try to profiling some applications on my MIPS based board running
linux kernel 2.6.30.

After profiling I used opannotate with flag --resource to show the result

but it can't find my source code properly

I put the source code and executable file in /var directory

Here are the warning message and execution result
-----------------------------------------------------------------------------------------------------------------
opannotate --search-dirs=/var --source ./app_mips
Using /var/lib/oprofile/samples/ for session-dir
/*
 * Command line: opannotate --search-dirs=/var --source ./app_mips
 *
 * Interpretation of command line:
 * Output annotated source file with samples
 * Output all files
 *
 * CPU: CPU with timer interrupt, speed 778 MHz (estimated)
 * Profiling through timer interrupt
 */
opannotate (warning): unable to open for reading: /home/weichihsun/app.c
/*
 * Total samples for file : "/home/weichihsun/app.c"
 *
 *    738 100.000
 */


 /* fast_multiply total:      2  0.2710 */
 /* slow_multiply total:    731 99.0515 */
 /* main total:      5  0.6775 */
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Any advice will be granted

Thanks!

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