"describe table" statement for the table backed by custom storage handler fail with CNF

1) describe customsdtable;

2) ADD JAR hdfs:///user/hive/customsdtable.jar;

3) describe customsdtable;

CNF is expected for #1 but even adding the custome serde, hive fail with following exception for statement #3

Error: Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. java.lang.ClassNotFoundException