BAdI - passing data between methods using an attribute

We have a BAdI named ZHRWPC_RQ, which displays a form for entry in MSS.

It has an Init method, and a check attribute. In the event a user changes the position number, I want to use the original position number before the change.

Under class interface ZCL_IM_HRWPC_RQ i created TMP_POS_NUM under attributes.

In the init method, I copy the position number to TMP_POS_NUM. In debug I can see the value in the field after the move.

in the Check method, I want to move the value from TMP_POS_NUM if the position number is invalid. However there is no value in TMP_POS_NUM.

I assume I am missing a step along the way, but am not sure what. i am referencing the attribute with me->tmp_pos_num. Is this the right way to access the attribute?

Any clues on how I can get the position number from the init method so I can use it in the check method would be appreciated.