@Michael_Pansolini - Have you tried to print whatever you mentioned above, using writeLine/Messagebox\Log Message activity ?? if so, what is the output you got?
You will need to use an assign activity if you want to change the value of Y.
Edit: When you set a default value for a variable is like having an assign activity in the begging of your workflow. if for some reason you want to change the value, you need to use an assign activity (or an activity with output value).