TagLib: String::prepare() - Unicode conversion error.

[mociml]

in Qt4.5,filename contains some Chinese words
    qDebug()<<"Read tag Name:"<<filename.toUtf8().data();
    TagLib::FileRef f(filename.toUtf8().data());
the following error will happen in some time,how to avoid this?
TagLib: String::prepare() - Unicode conversion error.
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