You'll need to make sure that the code you're calling in your expression has been embedded in your report. Go to Report >> Report Properties and select Code to see...

I found this blog post that does a pretty good job of providing tips to improve your reports. As mentioned, there are 3 components that impact report performance: data retrieval,...

Based on your row group structure I'm guessing that you want all 3 headers to repeat on each page. You'll also need to switch the static item properties for "KeepTogether"...

If you change your Row/Column Groups pane to Advanced mode, it will display your static group items in your tablix. You can find this setting by clicking the inverted black...