Meaning of the error message "Assertion `isIndexedCHW(d)' failed"

Hi all,
I’m working on implementing plugin layers of SSD network on Tensor RT 2.1.
Now, I’m facing the problem that when I try to parse the SSD network on Caffe prototxt with plugin layers to Tensor RT engine. The binary dumps and shows such error message:

helpers.cpp:39: nvinfer1::DimsCHW nvinfer1::getCHW(const nvinfer1::Dims&): Assertion `isIndexedCHW(d)’ failed

I have read the post: https://devtalk.nvidia.com/default/topic/1027394/tensorrt-3-0-ishufflelayer-cannot-transpose-tensor-from-chw-format-to-hwc/ . But it seems that that author’s problem differs from mine.

Could any one tell me the meaning of this error message, or give me some advises to solve this problems?

Thanks