InConsistency in volumes data from api

Hello

I have seen many keywords which had reasonable volume in October 2015, but since then had no volume,eg, ax paris, philip glenister, a x paris, salisbury cathedral, news now, now, star now, faceboook. I checked on keyword planner as well. Please see attached screen shot of keyword planner.

Also I have another set of keywords for which api returned high volume up to October 2015, then api returned volume = 0 in Nov-Dec for all previous 12 months, now api is returning volumes for all previous 12 months again. Please have a look at attached screen-shot.

Any Idea whats going on? something is not right.

Many Thanks

--
--
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~
Also find us on our blog and Google+:
https://googleadsdeveloper.blogspot.com/
https://plus.google.com/+GoogleAdsDevelopers/posts
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~
 
You received this message because you are subscribed to the Google
Groups "AdWords API Forum" group.
To post to this group, send email to adwords-api@googlegroups.com
To unsubscribe from this group, send email to
adwords-api+unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/adwords-api?hl=en
---
You received this message because you are subscribed to the Google Groups "AdWords API Forum" group.
To unsubscribe from this group and stop receiving emails from it, send an email to adwords-api+unsubscribe@googlegroups.com.
Visit this group at https://groups.google.com/group/adwords-api.
To view this discussion on the web visit https://groups.google.com/d/msgid/adwords-api/f7b17b49-5667-4c72-b85b-861cdf11f126%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.