Look at your payslip. If (as is usual) your employer deducts the pension contributions before applying tax to your gross earnings then the relief won't separately show up on your statement of tax credits.
It will only appear on the statement of tax credits if you have applied for it in respect of pension contributions made from net income. (If you do this then you'll also need to claim PRSI/health contribution relief separately at the end of the year - see the key posts). Pension contributions made via payroll should get tax and PRSI/health contribution relief at source by being deducted from gross before tax and PRSI/health contribution deductions are calculated.