Use MFMessageComposeViewController in iOS7, can't send iMessage / SMS for a while

this is my code:

MFMessageComposeViewController *controller = [[[MFMessageComposeViewController alloc] init] autorelease];
[controller setValue:[[[MyNavigationBar alloc]init] autorelease] forKeyPath:@"navigationBar"];

if([MFMessageComposeViewController canSendText])
{    
    controller.body = bodyOfMessage;
    controller.recipients = recipients;
    controller.messageComposeDelegate = self.orderBaseController;
    [self.orderBaseController presentModalViewController:controller animated:YES];
}

Screen image:

Problems:

• someTimes, it cannot send a message (in the application, click the send button, and ComposeViewController is rejected, but the message did not appear in the system message list)

• SomeTimes, an empty cell, for example, an image, will appear in the list of system messages. (Everything is empty, without message bubbles);

it works fine in a regular iOS device, only problems with iPhone4s with iOS7 (maybe iPhone4 too). the two guys who use my app are discovering this problem.

It seems like system errors, what should I do with it?