The federal program starts out by giving you the standard deduction, $6300 for single and $12,600 for married joint. You won't see a change in refund or tax due until the total of all the itemized deductions you enter exceeds the standard deduction amount. At that point, the program switches over to itemized deductions. You only get to take one or the other.
It may also be that you are paying AMT, in which case your refund or tax due would not change because property tax is added back to taxable income for AMT. For every dollar of decrease in regular taxable income from a property tax deduction, there is a dollar of increase in taxable income for AMT.