OpenCV:断言失败(img.depth() == CV_8U || img.depth() == CV_32F) && img.type() == templ.type()

I get this error from above and don't know how to avoid it. My aim is to get a screenshot and then perform a template matching on it to see if an icon is shown on the screen at this moment. Till now it's just the position of the icon. My code:I get this error from above and don't know how