Start by using the debugger to do two things:
1) Look at the content of
id
when you set the parameter value.
If it's not what you expect, you will not get the rows you expect.
2) Once loaded, look at the DataTable and see how many rows it contains before you start using it.
If it contains no rows, you know why you get nothing displayed...
Then start looking at your data to find out what you expected to get from the SELECT operation.
We can't do any of that for you: we have no access to your data or database!
But do yourself a favour: don't hardcode connection strings. Always use a config file or similar as otherwise you need to change your code between dev and release, and that means releasing untested software.
I do this:
Instance Storage - A Simple Way to Share Configuration Data among Applications[
^] but it's probably a little overkill for you.