jco3连接sap一直报错

错误如下：Exception in thread "main" com.sap.conn.jco.JCoException: (101) RFC_ERROR_PROGRAM: 'ashost' is missing
at com.sap.conn.jco.rt.MiddlewareJavaRfc.generateJCoException(MiddlewareJavaRfc.java:639)
at com.sap.conn.jco.rt.MiddlewareJavaRfc$JavaRfcClient.connect(MiddlewareJavaRfc.java:1313)
at com.sap.conn.jco.rt.ClientConnection.connect(ClientConnection.java:712)
at com.sap.conn.jco.rt.PoolingFactory.init(PoolingFactory.java:103)
at com.sap.conn.jco.rt.ConnectionManager.createFactory(ConnectionManager.java:189)
at com.sap.conn.jco.rt.DefaultConnectionManager.createFactory(DefaultConnectionManager.java:45)
at com.sap.conn.jco.rt.ConnectionManager.getFactory(ConnectionManager.java:178)
at com.sap.conn.jco.rt.RfcDestination.initialize(RfcDestination.java:760)
at com.sap.conn.jco.rt.RfcDestination.getAttributes(RfcDestination.java:598)
at com.sap.conn.jco.rt.RfcDestination.getAttributes(RfcDestination.java:28)
at src.dev.dao.test.connectWithoutPool(test.java:54)
at src.dev.dao.test.main(test.java:60)
Caused by: RfcException: [null]
    message: 'ashost' is missing
    Return code: RFC_INVALID_PARAMETER(19)
    error group: 101
    key: RFC_ERROR_PROGRAM at com.sap.conn.rfc.api.RfcOptions.checkParameters(RfcOptions.java:195)
at com.sap.conn.rfc.api.RfcApi.RfcOpen(RfcApi.java:78)
at com.sap.conn.jco.rt.MiddlewareJavaRfc$JavaRfcClient.connect(MiddlewareJavaRfc.java:1306)
... 10 more
大神何在啊