calibrate a camera and calculate the homography: assertion failed

edit

Hello!! I've a problem. I compiled the camera-calibration-program and there were no errors / warnings.

When I run the calibration-program and try to calibrate the camera with the images that are in my disk, I get an error-message that says:

"Assertion Failed:dst.channels<>> in unkown function , file ....modules 
\core\src\convert.cpp, enter code here`line 1277" in the function cvConvertScale() 
and cvCalibrateCamera2()

these two images resumes the results, after a click on continue in the image 1:

all the images appear one by one on the screen, but no output-file is generated.

Thanks for help in advance.