I wouldn't expect to see a table style in the Building Blocks gallery, but I would expect to see a Quick table.

Did you create your style like this:

1. Make a table and click inside it.
2. Go to the Table styles gallery on the Design tab and at the bottom of the gallery, click New table style
3. Use the dialog box to create the style

Don't forget to choose the option to save the style to the template (the option is at the bottom of the dialog box)