You are not listening to what I am saying.
Try to understand this. The surplus exists but it is not cash! It is made up of bonds.
When the bonds mature and must be paid off, as a country, we do not have the cash available to pay them off. So what do we do then? We borrow to pay off the old debt. This act should not add / subtract to the overall debt of the country.
The problem is that we are now paying out on a yearly basis, more than we get in taxes. So, if the trust is made up of bonds (bonds that we simply roll over, never pay off), we do not have cash to draw to cover these excess payments. So, as a country, we borrow more to pay them off. Thus, our debt increases.
For the record, in 2011, we started taking in less than what we paid out, on a non-intrest basis. You must remove interest from the equation because, again, as a country we do not run a surplus. So the interest expense used to pay out SS still adds to the general debt.