Trending Line Chart Dropping Issue

[Jberry]

We have a current app that is now live. However, on one of our trending graphs that show this year's data vs last year, the graph drops down in the current week which is really frustrating as I only want to see complete weeks. I'm trying to amend this and have added in a 'Today' function which didn't work and I'm not sure if it doesn't work because of the variables used to build the app. The current formula is as follows: 

if(vSelectedYr = vCurrentYear,
SUM({$<Year={$(vSelectedYr)},Week= ,Full_Week={'1'}> }[Sales Value Gross]),
SUM({$<Year={$(vSelectedYr)},Week= > }[Sales Value Gross]))

Using the Today function, I changed this to the following but the data remained the same and still showed the current week:

if(vSelectedYr = vCurrentYear, SUM({$<Year={$(vSelectedYr)}, Week= {"<$(=Week(Today()))"}, Full_Week={'1'} >}[Sales Value Gross]), SUM({$<Year={$(vSelectedYr)}, Week= >}[Sales Value Gross]) )

Any help would be much appreciated. An example of the chart dropping is below.

Example of the line chart issue