zmmailbox - ERROR: service.UNKNOWN_DOCUMENT (unknown document: GetFilterRulesRequest)

[peter@mxtoolbox.com]

I am having a wierd problem when trying to export filter rules via zmmailbox accross servers. I am using the following zmmailbox command

zmmailbox -u https://server:7071 -a admin@domain.com -p p4$$w0rd -m user@domain.com gfrl

ServerA - ZCS 5.0.9
ServerB - ZCS 6.0.1

From Server A I can run the command fine either against Server B or itself or any of the other members of the 5.0.9 cluster. From Server B however I can run the command against itself, but if I try Server A or any of the 5.0.9 machines in that cluster I get this:

ERROR: service.UNKNOWN_DOCUMENT (unknown document: GetFilterRulesRequest)

Any help as to why this is happening would be appreciated.

[peter@mxtoolbox.com]

When I opened the hood and looked at the SOAP requests it looks like 5.0.9 performs a "GetRulesRequest" while 6.0.1 performs a "GetFilterRulesRequest":

Does this mean that you just can't make zmmailbox calls from a newer version to an older version like this?