Searching using the citation

I have previously seen the Alien Registration for William Lum Chew on the website.

NAA: BP4/3, CHINESE CHEW W L

but I am unable to find it now.

I assume BP4/3 is the Series Number and "Chinese Chew W L" is the item title which is used as apparently there is no item number.

I have tried various Name Searches in "Immigration and naturalisation records" category but never see the BP4/3 series listed.

I have tried many Advanced Searches but to no avail.

Can anyone tell me how to find the above record?

Thanks

Dave