Plenty of kids have a hard time with pooping in the toilet, even after peeing is reliable. It's helpful to treat it as an entirely different stage of training. The children in a few young families I've known continued to ask for a diaper for pooping for several months after pee training was successful. It did not appear to confuse the children, who can be pretty sensible about what will work for them.
The urges and sensations for peeing and pooping are different, sometimes even painful, and can be complicated by diarrhea or constipation, or swing from one to the other. It usually takes a lot longer to poop than to pee – my grandson gets pins and needles in his legs from the pressure of the toilet seat by the time he's done. Some kids are very regular, some might poop four times one day and then skip two days, and never know what to expect. So it's often much harder, and this isn't your daughter's fault.
And some kids develop fear of the potty, or the sensations, or are terrified when they see a "part of themselves" in the potty and see it flushed away. This fear is hard to reason away in a young child, but usually they outgrow it when their cognitive functions are better developed. Parents can sometimes help this by understanding that the fear is real, and perhaps cheerfully encouraging the child to flush when the parent has a bowel movement. And explanation of "when food goes in, poop must come out" can be useful.
Most developmental specialists suggest that children be allowed to approach this challenge at their own speed, with parents acting as coaches, personal assistants, and cheerleaders. Kids do take on the challenge when they are matured enough physically and emotionally. Then it becomes a positive process for the child, and they are as proud as they are with any other new skill. Many parents report that any stage of training can take from one day to a couple of weeks when the child is confident he can do it.
Your daughter is old enough to understand the desirability of using the potty, but hasn't sorted out all the urges yet. If she tends to poop at a regular time, you might ask her to sit for a while and read to her, or line up a few of her toys to role-play successful pooping (my grandson still loves this if he's having an uncomfortable poop.)
If she's successful, be pleased but not overexcited for her, and don't assume it is necessarily anything more than a happy accident yet. After a few repeats, she'll probably start to get the "sequence of events" figured out.
If she's not successful, just cheerfully appreciate her trying, and express your calm confidence that she'll be able to do this pretty soon. She will. It just takes some kids more time, and the more pressure she feels to succeed, the less likely she is to get in touch with her actual bodily sensations.