WEBI report not reflecting after bex query changes

Hi

We have made changes in BeX query and these changes are not reflected in webi reports.The change is add some new variables to the query. and chnage existing variable.I follow the below process Instead of doing changes the existing query they take back up the query and did changes there provide another technical name.so in data tab we select destination and select the new technical name.

But it is giving the error when i try to map the error is like unable to connect the server.webipluin,web session from server after that webi server failed. Any body suggest me how it possible this strange behaviour. webi is not possible to refelct the changes after the bex query is updated. I follow the steps given but no use finally webi server fail.It is taking more work horus and panic each time the report doing from scratch after BEX changes. Finally report corrupted and webi server failed when we try to open the report.. I am using BOXIR4 SP15

Please suggest.