Program crashes during findContours() execution

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Hello guys

I got a problem with finding contours in the image. I'm trying to run a simple example on VS 2012 from the official site(http://docs.opencv.org/doc/tutorials/imgproc/shapedescriptors/find_contours/find_contours.html)

But the program always crashes with the following error:

OpenCV Error: Assertion failed (0 <= contourIdx && contourIdx < (int)last) in un known function, file ......\src\opencv\modules\imgproc\src\contours.cpp, line 1810

I've tried different modes CV_RETR_TREE,CV_RETR_LIST,CV_RETR_CCOMP but in vain.

I've also tried the sample from opencv/samples/cpp/connected_components.cpp, but always got another kind of mistake:

OpenCV Error: Unsupported format or combination of formats ([Start]FindContours support only 8uC1 and 32sC1 images) in unknown function, file ......\src\openc v\modules\imgproc\src\contours.cpp, line 196

I checked my code many times and red all manuals I'd found...all suggested samples are almost the same I begin to suppose the problem might consist into Visual Studio 2012 Also I noticed that all official samples run on Linux I use OpenCV version 2.4.3

Any ideas?