Thanks for reasuring me of this issue, I'll get to it when I can.

Thanks - must've been staring at a screen too long...don't know how I didn't see that. Back to the drawing board I go!

There needs to be a space after the comma. When you cast an array into a string without a delimiter, the default is a comma with no space. If you look at your screenshot again, you can see that a space is missing after the comma for the actual solution and there is a space in the expected solution.