I can't implement a simple box blur

Hi,

I'm very new to Adobe AE plug-in development and image processing in general, so I'm probably missing something very basic. I'm trying to implement a simple box blur using the supplied convolve method in the WorldTransformSuite1, but I am unable to achieve the blurring effect. I'm doing this just as a practice - I am aware of the FastBlur function in the AEGP suite.

Original image:

Output image:

The code in Render:

PF_FpLong convKer[9] = { 0.111f, 0.111f, 0.111f,

                                            0.111f, 0.111f, 0.111f,,

                                            0.111f, 0.111f, 0.111f };

ERR(suites.WorldTransformSuite1()->convolve( in_data->effect_ref,

                                                                             &params[BBOX_BLUR_INPUT]->u.ld,

                                                                             &in_data->extent_hint,

                                                                             PF_KernelFlag_2D | PF_KernelFlag_CLAMP,

                                                                             KERNEL_SIZE,

                                                                             convKer,

                                                                             convKer,

                                                                             convKer,

                                                                             convKer,

                                                                             output));

I have mostly been referring to the Convolutrix sample provided with the SDK, and my code looks (almost) identical to the sample. I can't figure out what exactly I'm doing wrong.