Insert rows in Subform not Working

Insert rows in Subform not Working

Hi, we're having problems inserting rows into a subform dynamically;
We have this instruction that suddenly stopped working:

input.Notes.insert(newNote);   

the syntax is correct based in the docs ( input.<subForm_linkName>.insert( <variable> );)
and  it was working fine until today. Now is throwing the following error:




Hope you can help us.
Thanks