indexing - Sitecore indexes multiple CD servers not consistent -

indexing - Sitecore indexes multiple CD servers not consistent -

i experiencing inconsistencies indexes on cd servers. have 4 cd servers, lets phone call them:

cd1 cd2 cd3 cd4

i have 2 databases servers, lets phone call them:

db1 db2

the configuration follows:

sitecore 7.2 cd1 , cd2 point db1 cd3 , cd4 point db2

i using eventqueue handle updates of cd servers. table getting populated , appears working, not consistently. if delete of indexes on of cd servers rebuild indexes , publish ca server see of index folders indexes on cd servers created. problem is, actual indexes empty on of cd servers , seems random.

any ideas on why indexes not beingness built same on cd servers?

indexing sitecore sitecore7 sitecore7.2