Query doesnt find existing data

SQL Server 2000 Enterprise

While testing an update script I found that a number of data rows are inaccessible using my query, though the data does exist in the table. I can browse records to find the data or query the record by some column names, but not by others.

For example:

SELECT name FROM tblPersonalInformation WHERE [ID Number] = 2358899;

would not find the data sought. However, if I put in:

SELECT address FROM tblPersonalInformation WHERE name = Doe, John;

the query yields the desired data. Many of the records queried display the specified data with no problem. I have found this problem to exist on a number of data rows, but cant figure out a reason. The front-end application displays the data without any apparent problems.

Ideas please.What is the datatype of [ID Number]?