SSRS 2008 Issues with mail merge fields in sub reports

I have a master report that I've created. I need to link a total of 7 subreports. I have inserted two subreports thus far. I have defined the parameters I need to flow down to my (Master)subreports and report level. I've created filters on each of the subreport to filter based on the parameters selected when the master report is run. The first report pulls the correct information through but the second one does not display any data where I've used expressions to merge information from the db. I am not sure of the appropriate way to link these subreports. For the subreports, I am basically removing the tablix and inserting a table. These reports are individual documents that make up a Master Contract.

If the same dataset gives me all the information I need, is there a way to set the variables housing the information I need on the master level and use variables to merge the data instead? Does it sound like I am handling subreports properly?

Any help is appreciated