Today I got my new bike pump. It is a two-way pump with pressure gauge, up to 100 psi, that I bought cheaply over the internet. When I tried to pump up my tire (Schrader valve) it seemed to be working, I mean, it pumped my tire. But the problem is that the gauge shows 20-25 psi even if I pump more and more until I can hardly squeeze the tire. Also, when I let the air out, it shows less than 10 psi. So the range is 5-25 psi let's say... On the other hand, when I place my thumb on the pump valve and squeeze the pump, it shows 30-40 even 50 psi (I can't hold it to higher psi range).
What can the problem be? Is it possible I am not putting the pump in the right position when I am pumping the tires?
Thank you in advance!