The field XXX cannot be totalled because of field overflow

I've got the following message in my ALV grid report:

"The field Hours cannot be totalled because of field overflow

Message no. 0K 051 "

The column reference is to CATSDB-CATSHOURS (QUAN 4/2).

The fieldcatalog is generated the following way:

Code:

METHOD fill_fieldcatalog.

DATA: r_wa_fieldcat TYPE lvc_s_fcat.

*--> CATSDB

CALL FUNCTION 'LVC_FIELDCATALOG_MERGE'

EXPORTING

i_structure_name = 'CATSDB'

i_client_never_display = flagged

CHANGING

ct_fieldcat = r_it_fieldcat.

...

In SE16 I can summarize this field .... but I have no idea why it works there and doesn't in my report.

I found OSS note 435362, it describes the same situation, but we already have the package level mentioned there....so it's not my case.

Any idea?

Thanks in advance,

Incho

Ps:My release is SAP R/3 46C and ALV grid is implemented based on cl_gui_alv_grid.