Adding header text to bapi_pr_create is not working?

I am using bapi_pr_create for creating a program that create Purchase requisition. What I want is to add header text to be added to newly created PR. I am using following snippet to upload the header text to the program.

prheadertext-preq_item = line_item.

prheadertext-text_id = 'B01'.

prheadertext-text_form = 'EN'.

prheadertext-text_line = 'test line'.

append prheadertext.

clear prheadertext.

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.

.

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CALL FUNCTION 'BAPI_PR_CREATE'

EXPORTING

prheader = zprheader

prheaderx = zprheaderx

testrun = ''

IMPORTING

number = result

* PRHEADEREXP =

TABLES

return = return

pritem = pritem

pritemx = pritemx

pritemtext = pritemtext .

prheadertext = prheadertext.

But the above method is not working.

Please suggest.

Hitesh.