calling dataset.show on a custom object - displays toString() value as first column and blank for rest

[Rohit Chaddha]

I have a custom object called A and corresponding Dataset<A>

when I call datasetA.show() method i get the following

+--------------------+----+-----+---------+-------+
|                        id|da|like|values|uid|
+--------------------+----+-----+---------+-------+
|A.toString()...|
|A.toString()...|
|A.toString()...|
|A.toString()...|
|A.toString()...|
|A.toString()...|

that is A.toString() is called and displayed as value of the first column
and rest all columns are blank

Any suggestions what should be done to fix this ?

- Rohit