Type conflict during a function module call (field length).??

Hello All,

I am trying to call a bapi for PO upload i.e, bapi_po_create1.

Everything is working fine ,the internal tables for bapi tables are also filled

But when my function module for 'bapi_po_create1' calls,just before i get a dump saying

"   Type conflict during a function module call (field length)."

The call to function module "BAPI_PO_CREATE1" is incorrect:

In the function module interface, it was stipulated that only fields of

a specific type and length can be specified under "POHEADER". The currently

specified field )"GT_POHEADER") has the right type, but its length is

  incorrect.

i am passing these tables in bapi.

CALL FUNCTION 'BAPI_PO_CREATE1'                                           

         EXPORTING

           poheader       = gt_poheader

           poheaderx      = gt_poheaderx

         TABLES

           return         = gt_return

           poitem         = gt_poitem

           poitemx        = gt_poitemx

           poaddrdelivery = gt_podelivery_address

           poschedule     = gt_poschedule

           poschedulex    = gt_poschedulex

           poaccount      = gt_poaccount

           poaccountx     = gt_poaccountx

           potextheader   = gt_potextheader

           potextitem     = gt_potext.

Please help me for this.