Try this:
1. Create a parameter in the main report that will contain the text data.
2. Create a parameter in the subreport for the text data. Put this on the report in the place of your "Text3" block.
3. In the subreport links, link from the parameter in the main report to the parameter in the subreport.
4. Set the main report parameter in your code instead of trying to update the text block.
-Dell