Wron input sent from checkboxes

I have a form that imports data from another form in the same data base and presents it as a set of checkboxes. I have entries imported.

When I create a new entry, the input works fine. When I edit the entry and change the selected checkboxes, then the input is a different set of selections (as reported by Debug->Info).

The code snippet is below:

y = "";

for each MarketSpaceLookup r in Products
{
if (y == "")
{
y = r.MarketSpace;
}
else
{
y = y + ", " + r.MarketSpace;
}
}
info y;

I am doing this because I want a view (product notes) that shows the Product name and the marketspaces for that product. Marketspace is one form, product, is another form that has a picklist based on marketspaces. I want the marketspace data to be updated when the product is updated. There does't seem to be a way to do this with Zoho (I tried importing the data as a hidden pick list, but the original data wasn't imported), so I am trying to hack my way around it. :)

Thanks.