When upgrading from 0.90 to 1.7 the transportClient stopped working

hi ,

i have upgraded the ES cluster from 0.90.10 to 1.7 , according the documentation .
i have upgraded the ES client to 1.7 jar too .
but when i try using the transportClient to fetch data from the cluster it doesn't find any .
there were some minor issue for compiling the project with 1.7 jar but i fixed them all .
what could be the reason ?
how can i pinpoint the problem ?