PowerBI Integration into Power Apps not working

Hi, 

I'm trying to integrate a power apps and power BI to create a system that allows teachers to add comments to their students. I've got a powerBI report that gets all the student and teacher data so that teachers can select the student they want to write comments about in PowerBI, and then am using a sharepoint list to store the comments. I added the power apps visual to powerBI and add the key field that I am also using in my sharepoint list and clicked to create a new app.

I'm now in Power Apps. I've connected a form to the sharepoint list so it will show me the comments, and want to then pass this form the data key field from the powerBI integration to find the comments for the selected student, but it's not recognising the field that I have passed through the PowerBI integration.

Here's the lookup formula I'm using to try and pass the key field from power BI to the form in power apps:

And here's my set up for the visual in PowerBI: