dsp error

hi Badri Narayanan，when i use the following function in the osd module,i found the return value is -6,so why? 

dsp_status = System_linkControlWithTimeout(
        SYSTEM_LINK_ID_DSP,
        SYSTEM_COMMON_CMD_CORE_STATUS,
        NULL,
        0,
        TRUE,
        waitTime
        );

TKS