Voluntary voter registration in Malaysia is either flawed or, more cynically, a systemic mechanism constructed to frustrate, not assist, the registration of new voters.
The figures speak for themselves. There are a total of around 15 million Malaysian citizens over the legal voting age of 21, but only 10 million or so are registered on the current electoral roll.
In other words, a third of voting age adults is outside the electoral process. That process is fundamental to any nation claiming any semblance of democracy.