After delete - no where clause

hi, Thank you for reading

scenario
--------

I set this to view training data for particular staff..

$rp_no=$_POST['rp_no']; // read from other page
$objGrid->where("rp_no = '$rp_no'");

for example; rp_no is 123 and system will view all training data belong to staff number 123 and it work fine.

rp_no training title
123 xxx
123 yyy

the problem is after i have done deletion on yyy or sorting , system will reload and show all data in entire database.

It seem like the where statement is lost.
Does anybody know how to fix this?

Thank you, Azwar

You must propagate the parameters by using linkparam method

$objGrid->linkparam("rp_no=".$rp_no);

Thank you.. it works..