I want to appear for PEGA Certified Lead System Architecture examination but, while booking the slot via Pearson Vue, I am not able to proceed as I am getting the below error:

Pegasystems Inc policy requires at least one of the following prerequisite exams must be passed: PEGACSSA, CSSA, PEGACSSA_v6 2_r, PEGACSSA_v6 2, PEGACSSA71V1, PEGACSSA72V1, PEGACSSA74V1, PEGAPCSSA80V1_2019, PEGAPCSSA85V1, PEGAPCSSA86V1, PEGAPCSSA87V1, PEGACPSSA88V1, PEGACPSSA23V1, PEGACPSSA24V1 before exam PEGACPLSA23V1 can be taken.

Please note I have already completed my CSSA examination (PEGACSSA71V1) long back in April 2015 and also, I have only one Pearson account associated with my ID. Could you please help me with this error and let me know how can I proceed?