after term tid changed, term disappear from the list, please help.

I have site A and site B. I need to export a certain node type from siteA to siteB.

there is vocabulary A in site A, vocabularyA has about 20 terms.

I have create vocabularyB in siteB, and also I have create 20 terms for vocabularyB as well. terms are the same in site A. after create the vocabulary and the terms, I went into the siteB's database(mysql) to try to match the vid and tid with siteA.

I have changed the vid of the vocabulary first to match with the siteA. after that, I change the tid of the terms to match with sietA's tid.

after I change the vid and tid. I login the siteB to see the taxonomy list. the problem is the vocabularyB's term list is empty.

summary, after I change the term's tid, the term list is disappear from the 'admin/content/taxonomy/60' page.

I don't have experience of mysql. Can anybody tell me how to get the term list appear again. if I change the tid back, then the term list come back again, but I can not export the node with taxonomy from siteA to siteB, I have to make tid the same in both site before the export.

Please help ! Thanks.