MFMailComposer is not working in iPhone 3GS

I have this piece of code for MFMailComposer working fine in the simulator and iPhone 4, but it crashes on 3GS. What is the reason and what is the way to resolve it?

I checked it wi开发者_如何学Cth breakpoints. mailPicker is not allocated with memory.

    MFMailComposeViewController *mailPicker = [[MFMailComposeViewController alloc] init];
mailPicker.mailComposeDelegate = self;

// Set the subject of email
[mailPicker setSubject:@"Somebody got place in my sh*t list"];
NSString *emailBody = @"I just added somebody to my s**t list";

// This is not an HTML formatted email
[mailPicker setMessageBody:emailBody isHTML:NO];

// Create NSData object as PNG image data from camera image
NSData *data = UIImagePNGRepresentation([self captureScreen]);

// Attach image data to the email
// 'CameraImage.png' is the file name that will be attached to the email
[mailPicker addAttachmentData:data mimeType:@"image/png" fileName:@"CameraImage"];

// Show email view 
[self presentModalViewController:mailPicker animated:YES];

// Release picker

[mailPicker release];

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If at least one email account is enabled on the device, the following call should return YES:

[MFMailComposeViewController canSendMail]

Conversely, if all accounts are disabled/removed, it will return NO.