Sum grouped in alv report

Hi experts,

I have a alv report (REUSE_ALV_GRID_DISPLAY) currently sum the Ctd column but sum all regardless of the value of the UM column

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I need to sum the values ​​of the Ctd column but grouping it by the code of the UM column as the following example

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I insert 'X' in the do_sum field of fieldcat of the Ctd and UM columns but did not work.

Please help.

Best regards,

Robert