If she's sleeping, you've already used the dating channel the maximum number of times (3) that you can use it in one day. Try again tomorrow. Or... adjust the clock so your Tamagotchi characters go to sleep, then adjust it again so they wake up, then try the dating channel again.
Try contacting her at a different time. DON'T CONTACT HER AT NIGHT. And also maybe you went to her 3 times already. When you go to her 3 times, you can't go on the dating show until the next day.