There is no schedule/section S for a C-Corp. 1120-S is a corporate tax return for an entity that elected to be taxed as a passthrough entity, where the income gets reported on the stockholders return and they pay the income tax. 1120-S is a completely different tax return than form 1120 for C-corps.
so is your corporation properly taxable as a C-Corp - form 1120
or as an S-Corp - form 1120-S?
if you filed form 2553 that means you elected to have the corporation taxed as an S-Corp. You should have gotten a letter from the IRS acknowledging the election and the first year it's effective.
if this is not clear see a tax professional
