ABAP Code

I am trying to run simple ABAP code. But it is not working.

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SELECT single obknr INTO mpos-obknr

FROM mpos WHERE warpl = record-warpl.

if sy-subrc = 0 then.

SELECT equnr

INTO i_plan_data-equnr

FROM objk

WHERE obknr = mpos-obknr.

i_plan_data-warpl = record-warpl.

APPEND i_plan_data.

ENDSELECT.

endif.

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record and i_plan_data are internal tables.

Code is not fetching obknr from mpos table.

Please suggest what can be the error.