Hi,
the jar should be placed under IntegrationServer\instances\default\lib\jars\custom instead of IntegrationServer\lib\jars.
But I would prefer to place the jar under IntegrationServer\instances\default\packages\WmJDBCAdapter\code\jars\static.
Subfolder static in this case to get the jar loaded during IS start and not during package start as it refers to the dll library.
Additionally you should consider switching to sqljdbc42.jar or better mssql-jdbc-6.2.2.jre7.jar.
When using Java 8 there is also a mssql-jdbc-6.2.2.jre8.jar available.
Regards,
Holger
#webMethods#Integration-Server-and-ESB