Don't understand the query logic

Hello dear all,

I have troubles by searching one indexed file.

The file was given in XML format before and I used a translator to make it JSON format.

This file looks like this:

{"metadataContainerType":
{"xmlns:ns2":"http://www.w3.org/1999/02/22-rdf-syntax-ns#",
"xmlns:ns3":"http:///namespaces/metadata/core/2010",
"add":
{"doc":
[{"name":"title","":"Hallo Welt"},
{"name":"format","":"work+xml"},
{"name":"created","":"2011-12-16T20:31:23.264Z"},
{"name":"last_modified","":"2012-05-10T07:29:05.451Z"},
{"name":"issued","":"2011-12-16T20:31:23.264Z"},
{"name":"id","extRef":"","":"example"},
{"name":"revision","":"0"},
{"name":"pid","pidType":"handle","":"hdl:
"},
{"name":"extent","":"38"},
{"name":"dataContributor","":"****"},
{"name":"project","id":"428746782346,"":"my project"},
{"name":"availability","":"public"},
{"name":"permissions","":"read"},
{"name":"agent","role":"author","id":"pnd:sdsfsf"":"someone, nobdoy"},
{"name":"dateOfCreation","notBefore":"1859","notAfter":"1919"},
{"name":"genre","":"prose"}
]
}
}
}

When I try to search for the title it works:

curl -XGET 'http://localhost:9200/blog/post/_search?q=title:Hallo%Welt&pretty=true'

it also works by looking for the "author"

curl -XGET 'http://localhost:9200/blog/post/_search?q=title:someone,%20nobdoy&pretty=true'

But any other field doesn't work. I tried to search in the field "availability":

curl -XGET 'http://localhost:9200/blog/post/search?q=availability:public&pretty=true'

This ends with no match.

Can somebody of you tell me what I am doing wring?

Nobody here who can help me?