# USB camera not detected, but seen in Device Manager

Dear all,

I am using openCV 2.2 for color tracking, and I have come across a problem.

When I am using the internal Lenovo webcam it works fine, but when I try to switch to external cam it's not detecting it.

I have tried with two different webcams (Microsoft and Logitech) but still no success.

I have also made sure that the camera is seen in the device manager.

I have also tried to disable the internal Lenovo webcam, and select

capture = cvCreateCameraCapture(-1);


but with no luck.

I get this error sometimes:

OpenCV Error: Assertion failed (func != 0) in unknown function, file ..\..\..\..\ocv\opencv\modules\core\src\copy.cpp, line 448