Hello sir, First, open only the outer cover. The plastic seal inside should stay in place, this piece should not be removed. Use the air blowing (OUT / Inflate) part of the pump. Press the pump head to fit the inner valve snugly. If the headgear does not fully contact the valve, air will not enter. Observe the mattress taking shape as you activate the pump during inflation. Stop inflating when the mattress takes its form, not when it hardens. Overinflation is not recommended. After inflation is complete, securely close the outer cap. This step prevents air from escaping. Applied this way the mattress will inflate without a problem.