Understanding qcompleter

[GrahamL]

Hi
Please help to understand QCompleter
Here is the code used to set up the completer
@
m_completer = new QCompleter(this);
m_fileSystemModel = new QFileSystemModel(m_completer);
m_fileSystemModel->setRootPath("");
m_completer->setModel(m_fileSystemModel);
m_completer->setCompletionMode(QCompleter::PopupCompletion);
m_completer->setMaxVisibleItems(10);
m_completer->setWrapAround(true);
ui.lineEdit->setCompleter(m_completer);
@
When I run this I seem to get inconsistent behaviour
At time the completion popup is not displayed

Is there anything obviously wrong with my code or has anyone else any ideas as to why this happens

I have built the completer example supplied by Qt and the same behaviour happens