mySubCat.Path="'"+ Eval("NodeAliasPath") +"'"; will get you the rendered documents URL wrapped in single quotes. Remove the single quotes. If you need to get everything below the current document then you need this string
/Node1/Node2/% returned to the Path property, not
'/Node1/Node2' which is what you're string will return which is essentially a single document.
Adding the % at the end, is a wildcard search parameter. If you look in the database you'll see how things are stored and have a better understanding of why things are like they are.
The structure like so is stored like so:
--About Us (/About-Us)
---Contact Us (/About-Us/Contact-Us)
----Contact Form (/About-Us/Contact-Us/Contact-Form)
So if you want everything below the /About-Us node you need to enter
/About-Us/% which will return the last 2 records. Then if you only want to go 1 level deep and not return the form, you enter the maximum level = 1.