Problems with resource asignation over a user

Hi,

chain:

https://hst-api.wialon.com/wialon/ajax. … mp;params=[{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000000100000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000000400000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000001000000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000004000000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000040000000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000200000000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0000200000000"}},{"svc":"user/update_item_access","params":{"userId":18701505,"itemId":18701508,"accessMask":"0x0100000000000"}}]&sid=

answer: "[{"error":6},{"error":6},{"error":6},{"error":6},{"error":6},{"error":6},{"error":6},{"error":6}]

can I know why error?

thanks