logstash nginx pattern thows the result in _grokparsefailure

I have an nginx patteer which was successfully tested in grokcontructor but when adding it to logstash 1.5.3 the logs do end up with _grokparsefailure

Here is a sample of my access.log:

207.46.13.34 - - [14/Aug/2015:18:33:50 -0400] "GET /tag/dnssec/ HTTP/1.1" 200 1961 "-" "Mozilla/5.0 (compatible; bingbot/2.0; +http://ift.tt/MKuKRM)" "-"

and here is the nignx pattern:

NGUSERNAME [a-zA-Z\.\@\-\+_%]+
NGUSER %{NGUSERNAME}
NGINXACCESS %{IPORHOST:clientip} %{NGUSER:indent} %{NGUSER:agent} \[%{HTTPDATE:timestamp}] "%{WORD:verb} %{URIPATHPARAM:request} HTTP/%{NUMBER:httpversion}" %{NUMBER:answer} %{NUMBER:byte} "%{URI:referrer}" %{QS:referee} %{QS:agent}