Dynamic Linkbutton with asp:calendar

I have a asp:calendar that dynamically adds Linkbutton controls that come from the database.  I am unable to figure out a way to find out what linkbutton is clicked.  What I am trying to do is when the linkbuttons are generated. I want to be able to click the linkbutton and be able to know which button I clicked so i can have a popup display additional information for that link that was clicked here is my code below.
 
//THIS CODE ADDS THE LINKBUTTONS TO MY CALENDAR
foreach (GridViewRow grvRow in gvappointments.Rows) {
if (e.Day ...