Hi,
the error comes from the assembly, so you should look for the error on the assembly side, e.g.: MSDN
This points to a problem with your enumeration, which is why it shows up in the second iteration of your for loop. It looks like (on my system) only one Voice is installed and you should probably not hard code the Number of iterations to 3. I would look for an approach that first detects the number installed and passes it to the loop.
P.S.: Also the Choose the voice control will probably not work like you want, since it's not clear, when it is read. My guess is: right at the start, while it's populated only after the for loop is complete.
