Read family parameter using Python Dynamo

Dear network,
I am trying to read family parameter values (which are not shared parameters) using following command. Yet it outputs an empty list. But this method works fine with shared parameters. Does that mean I cannot read family parameters which are not shared?

elempars= # loop over elements to get instance parameter. This should be a shared parameter to retreive data.
for i in UnwrapElement(elements):
for j in i.Parameters:
# Check if instance parameter is shared.
if j.Definition.Name == parameter:
# check if the instance parameter value if the GUID matches.
parameterValue = i.get_Parameter(j.GUID)
elempars.append(parameterValue.AsDouble())

Try
element.LookupParameter(parameter).AsString()
Or AsDouble(), AsElementId(), etc. depending on your data type.
image

try to change:
parameterValue = i.get_Parameter(j.GUID)
to:
parameterValue = i.get_Parameter(j.Id)