Problem with CCK computed field

At what point lnid is created? I have a CCK computed field that does some processing based on the lnid. When I create a new node, the result of the computed field is missing the lnid part. The code part of my field is something like

($node->lnid+50)*2;

Assuming lnid is 1, the output would be (1+50)*2 = 102. However, every time I create a new node the result is 100 so it apparently disregards the lnid. If I go to modify the node and just hit the Send button without actually changing anything, everything is ok. I assume this has something to do with the code of my CCK field being eval'd before the lnid is assigned. Any ideas how to get around this?

Mikko