I was finding the period of crab pulsar using efsearch(xronos)

Question

I was finding the period of crab pulsar(one orbit data from ASTROSAT/laxpc) using efsearch (heasarc/xronos). Despite considering period = 33ms, I am not getting sharp peaks at higher Resolution for period search(10^-8). I guess I am making mistake in selecting various inputs like Phasebins/Period.

I got the Best period at : 1e-8 = 0.03299998000000 , with no sharp peak

1e-7 = 0.03300007000000 , no sharp peak

1e-6 = 0.03229730000000 , no sharp peak

1e-5 = 0.03302100000000 , no sharp peak

1e-4 = 0.03340000000000 , sharp peak

I am new to this.

So, What is the relation between time-bin, no. of phase bins, and the specified period while folding a light curve using efsearch? Also, What is a phase bin?