Cannot parse qml content(weird error)

[stereomatching]

Sometimes the parser can not parse the qml content correctly
It always give me error messages at runtime like
"can not bind function to double", "no reference to xxx"

example

@
Item{

//.....
PhotoViewer{
//......
}

}
@

For some mysterious reason, the codes can't work
But when I change the file name from PhotoViewer to PhotoViewer2
it works.

@
Item{

//.....
PhotoViewer2{
//......
}

}
@