I think you'll have to turn 'Show Only Relevant Values' off. It's hard to say exactly without your packaged workbook. If you'd like some help preparing a sample, take a look at the 'New To the Community' link on the homepage - https://community.tableau.com/welcome , then take a look at the suggested reading on the right hand side. The Tableau Forum Guidelines listed there discuss some ideas on creating a sample workbook. The quickest is usually to replicate a sample using the Superstore sample data provided with Tableau.
(Note to self: V10.1 workbook.)
I'm trying to sort through this.
You can give the users a filter to let them select what measures they want to see. In the attached I have added that to the bar chart sheet.
There are drawbacks to this. You can't limit the measures displayed in the filter list. All or nothing. So if you have created 100 calc measures, users are going to see those along with the list of data source measures. This may be confusing (and messy) for the user.
You can't show dimensions in the same way. It looks like you are trying to mix selection of dimensions and measures in here. I see what you are trying to do in the [Variable 1 Selected] calc. That is how you let the user select which dimension to view, but you can only do that with one dimension at a time. If you want them to select both [WT2014 Weight] AND [%WTFac], (to pick two dimensions)), you will have to have two calcs to manage that.
You'll notice that a parameter will let you select only one value at a time. That's why you'll need two calcs (and therefore two parameters) to manage two dimensions at a time.
In your [Variable 1 Selected] calc, you are mixing dimensions and measures. That's not going to work.
So having said all that, let's talk about what you're really looking to do here. Give some examples of what a user might try to do here, and let's discuss ways you can make it happen.