Hi,
May I ask what is NREQ? Is it your own customized transaction types for RFx?
If you are using 'create RFx' button in SC, is there any pop-up window to select specific RFx transaction types? If not, I am afraid that you should set the values for attribute TEND_TYPE for user in ppoma_bbp. It is probably that the first or the last value of this attribute will be set as default transaction type.
BR,
Ivy