Ren, having spent literally hours on some days trying to get DS to sleep, I would say give it 15-20 minutes and if it's not happening then do something else for a while. Watch her closely and the next time she appears sleepy, try again. Believe me - I know how hard it is when they obviously NEED to sleep but just won't. Unfortunately, the more you push it the harder it gets!

If you're getting to the stage where she's getting overtired then maybe just use the HAB/sling whatever if that works. Carry her around for a day or two so she gets some rest, then once her system is 'reset' try putting her down for naps again.

Good luck