CSSA v5.5 is an acceptable prerequisite for CLSA 7.1. I suspect that you may be trying to register for your CLSA certification using a different Pearson Vue ID than the one that you have used previously. I will send you an email directly with the email address that we have associated with your previous Pearson Vue certifications so that you can confirm that you are using the same ID that has the rest of your Pega certification history associate with it.
I am also facing the same error when trying to register for the CSSA exam. Earlier i had used the "firstname.lastname@example.org" ID. But now, with this ID i am being told i have not completed the pre-requisite exams.
I have created one Pearson account with alternate mail id which is added to my Primary PDN account. But while scheduling the exam I am receiving the error "Pegasystems Inc Policy requires that a prerequisite xam must have been passed in order to register for exam PegaCLSA71V1". Primary mail Id for PDN account is my company Id and alternate mail id added to PDN account is my gmail id. Pearson account is created with the same gmail id. Can someone help on this issue?