If you need to do this in the load script, then you can't use the list box selection as the list box does not "exist" until the load script completes. To get the value to the load script, you can set a variable using an input box, or create a trigger on the list box field to save the current selection value in a variable - and then use the variable in the script. Something like:
SQL EXECUTE RP_ERRORREPORT '$(vAppCode)';
Thanks for the Answer.
Here is full scenario.
I have a List box or may be some other controls which have multiple values.
e.g. ABC,XYX, XXX, EEE, DDD etc
I have created a variable vAPP
LET vAPP ='ABC';
now I passed this variable to my SP.
SQL EXECUTE RP_ERRORREPORT '$(vAPP)'; === SQL EXECUTE RP_ERRORREPORT 'ABC';
it works fine and load data in the chart.
But when I select some different value from List box say 'XXX', then I want variable vAPP value changed to 'XXX' and my SP called again.
SQL EXECUTE RP_ERRORREPORT 'XXX' and load the data on chart based up on my current value of vAPP.