PHP and SQL help

I am new to PHP and MySQL, and appreciate your help greatly. I create a simple one table database to list the seminar list. The fields are name of the speaker and the title along with other information. I used phpMyAdmin-2.2.1 to input the data and see that all the fields , including the fields that I couldn't get the values as described below, have proper values. When I retrieve all the fields from the same database from my little PHP program and display the result on a webpage (I use "select * from seminars order by datestr desc" to retrieve the records), I noticed that some records missed the name of the speaker field. Of about 80 records, I have 10 records have this problems. Does anyone have any idea what's going on here? Thanks for the help. Yua Lu