为什么我安装river，启动之后报Failed to load class with value [jdbc] 错误

我的es版本是1.7.2，jdbc是对应的1.7.2.1，然后连接的数据库是sqlServer数据库，为什么es启动报错
org.elasticsearch.common.settings.NoClassSettingsException: Failed to load class with value [jdbc]
at org.elasticsearch.river.RiverModule.loadTypeModule(RiverModule.java:87)
at org.elasticsearch.river.RiverModule.spawnModules(RiverModule.java:58)
at org.elasticsearch.common.inject.ModulesBuilder.add(ModulesBuilder.java:44)
at org.elasticsearch.river.RiversService.createRiver(RiversService.java:138)
at org.elasticsearch.river.RiversService$ApplyRivers$2.onResponse(RiversService.java:274)
at org.elasticsearch.river.RiversService$ApplyRivers$2.onResponse(RiversService.java:268)
at org.elasticsearch.action.support.TransportAction$ThreadedActionListener$1.run(TransportAction.java:113)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: jdbc
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at org.elasticsearch.river.RiverModule.loadTypeModule(RiverModule.java:73)
... 9 more

是不是sqlserver对应的jar包也有版本的限制，请大神帮帮忙，在线等。谢谢了！