Having issues using getSuperGrid

Hello everyone,

I'm having some troubles with a script I'm writing, and I hope someone here can help me.

I'm trying to retrieve a Super Grid in my javascript, but i'm having the following error :

"Unable to get the property " elementObject " of a null or undefined reference".

The code that crashes :

var superGrid= Xrm.Page.getSuperGrid("requestdocuments");
var allRecords= superGrid.editgrid.getAllRecords();

FYI, the environment is an online CRM 2016.

Thank you in advance for your help,

Samuel.