2 way guitar Pulloff problem?

In many songs solos there are pulloffs the require doing two pulloffs at once. like 19p17p15. when i do it i can hear me pluck the 19th, but when i pull off to 17 and 15 i can hardly here them. i pushed harder on the string then pulled off but still they were too quiet to be heard. i have been trying it for quiet some time now and i still cant get it. i have come to the conclusion that it is not my fault, its my guitars. it is a squire strat and im using a frontman 15g amp, im i right or am i doing something wrong?