Napping and Sleeping in crib

aimalama

I'm trying to get my LO to nap in her crib during the day.  She sleeps in a bassinet in our room at night (it is inclined) so I have made her crib mattress also inclined.  She absolutely hates her crib!  I try to put her in there when she is showing signs of being tired, but as soon as I put her down in there she cries.  The pediatrician said that I should start letting her cry up to 15 minutes.  I feel awful doing that and by the time I get her she has worked herself up so much that it's then difficult getting her calmed back down.  I fear what it will be like to get her to sleep in there at night.  Anyone have any advice or is anyone else going through this?