I completed a cashless sell in January 2016. The income and taxes withheld were reported on my w2. The gain was also reported on my 1099b but it doesn't show any taxes being withheld. My refund went down after inputting the information as is. Is

The problem isn't that the 1099-B isn't showing taxes being withheld.  The cash raised by selling stock "for taxes" went back to your employer, who paid the government(s), and included those taxes on your W-2's various "taxes withheld" boxes.  You can ask your payroll department about that.

The problem is that you are using the wrong basis to report the sale.  In a "same day" sale your per share basis is the same per share fair market value used by your employer to calculate the compensation reported to you on the W-2.  A typical same day sale shows a small loss due to selling commissions and fees.

Tom Young