Execute Javascript in Safari using KM variable (SOLVED)

I have a questions about using a KM variable in a execute javascript in safari step.

I have tried to follow the example here: Get KM Variable into Javascript Action however it does not seem to work for me and I am wondering what I might be doing wrong.

When the text for script is manually entered it works fine so I know the actual script works.

There is an element that needs to change in the script so I created a variable to hold the complete text for the script.

However, when I use the variable in the execute step nothing happens

I've attached a image of the steps
Step 1 sets the variable up to be: customizeProduct('5e98223a2b5a8','tapestry');
Step 2 initializes the document.kmvar object.
Step 3 executes the javascript using the variable set up in step 1
Step 4 (disabled) shows the manually entered script which works

Any help greatly appreciated

I worked it out! Simply adding eval and bracketing the variable means it works: