Hi Manidhar,

According to your description, you want to add a row group or a column group in a tablix and the group on expression is specified as a field, right?

In Reporting Services, a group has a name and a set of group expressions that we specify. The set of group expressions can be a single dataset field reference or a combination of multiple expressions. To add a group based on a specific field, we can drop the field on the Grouping pane (Row Groups, Column Groups). Or we can select and right click the cell in the data row, select the Add Group option to add a column group or row group. Specify the group expression with the specific field.

Reference:
Understanding Groups (Report Builder and SSRS)
Add or Delete a Group in a Data Region (Report Builder and SSRS)

If you have any question, please feel free to ask.

Best regards,
Qiu

Hi Manidhar,

Check the similar thread

https://social.msdn.microsoft.com/Forums/sqlserver/en-US/19293b0d-3cf9-4d1c-a488-ebc433e70b09/grouping-in-ssrs-report?forum=sqlreportingservices