Objective-C NSURL URLWithString appears to fail when using variable

So this is my first posting on StackOverflow, so excuse me if my request is not well formed.

I am attempting to load a variable with type NSString into an NSURL with the following line:

audioPlayer = [[AudioPlayer alloc] initPlayerWithURL:[NSURL URLWithString:aArchiveItem.streamURL] delegate:self];

And in AudioPlayer implementation I am using:

-(id)initPlayerWithURL:(NSURL *)url delegate:(id<AudioPlayerDelegate>) aDelegate {
    self = [super init];

    delegate = aDelegate;

    queue = [[AudioQueue alloc] initQueueWithDelegate:self];

    fileStream = [[AudioFileStream alloc] initFileStreamWithDelegate:self];
    [fileStream open];

    request = [[AudioRequest alloc] initRequestWithURL:url delegate:self];

    return self;
}

When I hardcode a URL string(e.g. URLWithString:@"http://www.example.com") the call to the audioPlayer work flawlessly, but when attempting to populate it with the value of aArchiveItem.streamURL it fails…

What am I doing wrong here?