Google是您的朋友:很好，经常拜访他.与在这里发布问题相比，他可以更快地回答问题.

使用您的主题作为搜索词进行的快速搜索获得了近400万次匹配: ^ ]

将来，请尝试至少自己进行基础研究，不要浪费您或我们的时间.

Google is your friend: Be nice and visit him often. He can answer questions a lot more quickly than posting them here...

A very quick search using your subject as the search term gave almost 4 million hits: www.google.co.uk/search?sourceid=chrome&ie=UTF-8&q=Operation+is+not+valid+due+to+the+current+state+of+the+object[^]

In future, please try to do at least basic research yourself, and not waste your time or ours.