分享链接到微博，还没有切到微博，就报错了

UMSocialMessageObject *messageObject =[UMSocialMessageObject messageObject];

UMShareWebpageObject *shareObject =[UMShareWebpageObject shareObjectWithTitle:titleStr descr:dscStr thumImage:[UIImage imageNamed:@"icon"]];

shareObject.webpageUrl = weblinkStr;

messageObject.shareObject = shareObject;

[[UMSocialManager defaultManager] shareToPlatform:shareMedia messageObject:messageObject currentViewController:[SGGame instance].platformDelegate completion:^(id data,NSError *error)

{

if(error)

{

NSLog(@"************Share fail with error %@*********", error);

NSString *failstrPre = @"fail#";

NSString *failstrTotal = [NSString stringWithFormat:@"%@%@", failstrPre, error];

}

else

{

NSLog(@"response data is %@", data);

}

}];

点击执行上面的代码后，直接报错“please check the image parameter wether is valid”，没有切到微博去。看这个错误的描述，我就只是分享一个https的链接，也需要设置什么图片吗？thumImage:[UIImage imageNamed: @"icon"]这个icon的位置必须要填？需要怎么填呢？