VelocityViewServlet : Error processing the template

Invocation of method 'getDistinctFieldValues' in  class $Proxy7 threw exception class org.springframework.transaction.CannotCreateTransactionException : Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Cannot open connection
org.apache.velocity.exception.MethodInvocationException: Invocation of method 'getDistinctFieldValues' in  class $Proxy7 threw exception class org.springframework.transaction.CannotCreateTransactionException : Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.GenericJDBCException: Cannot open connection
	at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:309)
	at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:207)
	at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:357)
	at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:135)
	at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:271)
	at org.apache.velocity.Template.merge(Template.java:296)
	at org.apache.velocity.tools.view.servlet.VelocityLayoutServlet.mergeTemplate(VelocityLayoutServlet.java:253)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doRequest(VelocityViewServlet.java:434)
	at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doGet(VelocityViewServlet.java:392)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
	at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
	at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:283)
	at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:767)
	at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:697)
	at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:889)
	at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
	at java.lang.Thread.run(Thread.java:595)