A problem during restoring database from PostgreSql 6.5.3/7.1.3 to 7.4

Hello ！

    I can dump data from old dababase(Postgresql 6.5.3), but new problem came out when I restore the data to postgresql
7.4.

    It went out during the COPY command, if I do it in such command lines:
    1.     pg_dump news -f pgsql-database-news.sql        #in old system with postgresql 6.5.3
    2.     su - postgres                                #in new system with postgresql 7.4
    3.     createdb -T template0 news
    4.     psql news < pgsql-database-news.sql
------
ERROR:  missing data for column "user_id"
CONTEXT:  COPY newses, line 1:
------

    But if I do it in such command line, it works well :
    1.    pg_dump -d news -f pgsql-data-news.sql      #in old system with postgresql 6.5.3
    2.     su - postgres                                #in new system with postgresql 7.4
    3.     createdb -T template0 news
    4.    psql news < pgsql-data-news.sql

    The database looks fine but I'm not sure it is really good. 
    Then I try postgresql 7.1.3, and I found that it is very well from 6.5.3 to 7.1.3 in the two kind of
command line.
    Later I also found that it likes the 6.5.3 when I dump/restore the data from 7.1.3 to 7.4.

    Could Anybody explain it? Whether there is a version with big change between 7.1.3 and 7.4 or not? 　

　　　　　　　　
                 
　　　　　　　　　　　　　Yours Wind Wood
　　　　　　　　　　　　　　windwood@jingxian.xmu.edu.cn
　　　　　　　　　　　　　　　　　2003-12-09