I developing a system monitoring I need to log all execute command,stack trace,i/o what i mean is, i need to get an application script code that running externally from this project did anybody know how to code this thing

my Page contain a gridview with a sqldatasource that have a parameter programatically set value after sqldatasource run a select statement to bind data i need to have a selectedindex of row for select button but it gets me error of index out of range I have done checking.. it seems to me that this gridview get the selectedindex value after twice postback let say i click on index 1 another click on index 2 the result is selectedindex = 1 that's the problem