Typical TDS meters don't really measure Colloidal Silver - I know alot of sellers say this, but that's mostly due to confusion.
Having said that, there are a few factors to consider before drawing a conclusion on your results.
The first question I'd ask is whether or not your generator shuts-off at a given point in processing?
The second thing I'd ask is whether or not the solution is showing any signs of color change?
With that said, the next questions will depend on the above answers.