With holding tax convertion problme doc currency to QAR

Hi Frds,

I have one problem regarding withholding tax recently we created withholding tax certificate.My org local currency is USD and foreign currency is QAR.in programme my abaper has given in call function CONVERT_TO_FREIGN_CURRENCY has given

client           = sy-mandt

date             = sy-datum

foreign_currency = 'QAR'

local_amount     = wa_bseg3-dmbtr

local_currency   = 'USD'

importing

foreign_amount   = lv_dmbtr_alt

exceptions

  no_rate_found    = 1

  overflow         = 2

  no_factors_found = 3

  no_spread_found  = 4

  derived_2_times  = 5

others           = 6.

But in local currrency place i am asking to give wrbtr and value which one has to give?

now we have given USD to QAR,if document currency is USD value is coming correctly in QAR.But document currency other than USD covertion is coming worngly.That's why my concern is document currency directly has to convert to QAR.

Anybody can suggest for this issue.

Regards,

Nivas.