What will be reason for GPS not getting selected in Chrony?

Question

I'm trying to get the precise time using PPS from the GPS module using the chrony. But every time I'm getting '#-' before the Gps as shown below

MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
#* PPS0                          0   4   377    14   -302ns[ -374ns] +/- 1110ns
#- GPS                           0   4   377    13   -215ms[ -215ms] +/-  102ms

My chrony.conf file is as follows

#Mange the clock slower for less jitter
minsamples 10

# set larger delay to allow the NMEA source to overlap with
# the other sources and avoid the falseticker status

refclock PPS /dev/pps1 lock NMEA trust prefer
refclock SHM 0 offset 0.395 delay 0.2 refid GPS trust prefer

#refclock SHM 0 poll 3 refid GPS1
#refclock SHM 1:perm=0644 refid GPS2

keyfile /etc/chrony/chrony.keys
commandkey 1
driftfile /var/lib/chrony/chrony.drift 
log tracking measurements statistics
logdir /var/log/chrony
maxupdateskew 100.0
dumponexit
dumpdir /var/lib/chrony
# if local stratum is configured and there's a local clock issue, the PPS changes 
stratum to match this stratum 10
allow
logchange 0.5
rtconutc

Here can I reduce 1110ns to 100ns by doing any modifications in conf file?. Basically, my doubt was if I'm using two sources from which one will be the PPS socket and the other will be GPS shared memory driver so will this combination be okay to get less offset? or do I need to use only GPS socket with PPS socket or GPS shared memory with PPS shared memory.