Why do I get this error message?
* I have a data set with this name on the page
* It's a dynamic page
its not the id, you need to right click go to properties to get the id
The dataset is not that name in the code. It is dataset5 and not what you are calling it.
You can see the id name of the dataset faintly at the top left of the dataset in the pic with the dataset settings showing, this is what you should be using in your code.
Right click on the dataset and choose properties and you can change the id name there.