the onchange code is not correct:
onchange=""document.eCredit.eCredits_1_ID_Add.value = document.eCredit.eCredits_1_creditoption_Add[document.eCredit.eCredits_1_creditoption_Add.selectedIndex].text""
should be:
onchange="document.eCredits_1_ATC_<?php echo $row_CredOptions["cred_id"]; ?>.eCredits_1_creditoption_Add.value = document.eCredits_1_ATC_<?php echo $row_CredOptions["cred_id"]; ?>.eCredits_1_Price_Add[document.eCredits_1_ATC_<?php echo $row_CredOptions["cred_id"]; ?>.eCredits_1_Price_Add.selectedIndex].text"