Why doesn't it work when I import nodes to the database?

I'm converting a Textpattern site to Drupal, and import all the information to the database. I get all the nodes and terms in place and I can see them on the site. But when I try to make a new one, the normal way through the site, it tries to overwrite the existing nodes/terms. What do I do wrong?

For the nodes I insert the data into node, node_revisions, history, node_comment_statistics
and for the terms into term_data, term_hierarchy, term_node

Are there any tables that I have forgotten, or why doesn't the system recognise that the nodes are there, when I try to make new ones?