Convert a text in a Dictionary List

Hi,
I'm creating an interface where I load a local variable. This local variable is a cdt, so I use the function cast to convert it. I need to populate a field of this variable, so I build the following string:
{{Id:1},{Id:2},{Id:3}}.
Now I need to convert it in a dictionary, but it always return me an empty value.
I would like to know if you have some idea about it.
Thanks in advance.

OriginalPostID-250259