Call transaction 'ZYXYX' using bdcdata not work..What is the data to check?

data bdcdata type bdcdata

data lw_opt ctu_parames.

bdcdata-program = 'ZXZXZX'.

bdscdata-dynpro = '100'.

append bdcdata.

bdcdata-fnam = 'so_kunnr-low'.

bdscdata-dynpro = '234352453'.

append bdcdata.

Call transaction 'ZXYXYXYX' using bdcdata options from lw_opt.

results the transaction is called but the parameters is empty !! What is the value that I must check ?

Any idea?