Sometimes on a net, net control acknowledges a check-in that I haven't heard. That is, I hear some check-ins but not others. Not poor signal, just silence. But net control hears it. Why might that be?
[Me: new ham, Yaesu HT]
Congratulations on your new license! Since you referenced an HT, it would seem you are talking about VHF or UHF nets.
VHF and UHF signals are generally line of sight communications. If your antenna is too low, a signal can be blocked by buildings, hills, etc. If the net control station (NCS) has better elevation or antenna height, the NCS will be able to hear more stations.
Another possibilty relates to gain/sensitivity. If the NCS has a higher gain antenna system or a more sensitive receiver, the NCS will be able to receive weaker signals.
So if you are using your flexible rubber antenna on your HT and the NCS is using a collinear antenna on a 50 foot tower, the NCS will generally hear more stations than you can. Work to improve the height and gain of your antenna system.
Of few other less likely possibilities are:
Your squelch is set too high. Try opening the squelch to see if you can hear some of the stations that the NCS can hear.
If you are using a repeater, make sure you have the correct transmit CTCSS tone programmed and don't initially use a receive tone.
If on a repeater, make sure you are not operating upside down (transmit and receive frequencies transposed).