title: Control executing of hidden subreports inside tablix (SSRS)
body: <p>I am using SSRS2008R2, On my main report there is tablix inside tablic there is row (merged cells) which contain sub report. Subreport is initially hidden and toggled by other cell. 
  <img src="https://i.stack.imgur.com/aZm0X.jpg" alt="enter image description here"><br>
  When I preview my report it is working fine, I can show and hide sub report clicking on "referat" cell.<br>
  But my problem is that for every row inside tablix SSRS generating subreport, That task take a lot of time. I want to make my hiden reports do not contain data and do not call SQL during first execution of report when they are hidden. I want to subreport do SQL call just before user expand (show). <a href="https://stackoverflow.com/questions/10139869/hiding-sub-report-in-ssrs-based-on-parameter-and-not-executing-the-stored-proce">I know that I should pass different params to sub report so it can realize to do or not calling sql (sprocs).</a>  .
  But I do not know how to pass that parameter to subreport, or how to check is something hidden or not so i can change my param to subreport.<br>
  <img src="https://i.stack.imgur.com/yRjYT.jpg" alt="Am I setting params at wrong plase"></p>