[web2py] jqgrid question

[William]

I want to display a jqgrid table on the web, I set that the table
shows 20 records as default. And right now I have 23 records in total.
Therefore, its page number should be 2. However, If I don't click the
bottom-right, its page number is always 3, how can I do to correct it?
Thank you for your help.