HELP! MQ Series error when using sample 'amqsput' - reason code 2035

I'm trying to establish exactly why my UNIX user (t20ora) can't "put" messages on and "get" messages from the test queue, (as provided by the MQ Series install), but am up against a brick wall!

My UNIX Environment:
- Solaris version:
SunOS sauron 5.9 Generic_118558-02 sun4u sparc SUNW,Ultra-4
- Websphere MQ Series v5.3 (installed from 'C44J8ML.tar.Z', downloaded directly from IBM's website)

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Actions undertaken: Running the test 'put' and 'get' from the designated queue:

Trying to put & get a test message to the designated queue gives the following problem....
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- As mqm user (the user whom MQ Series was installed as)

sauron:mqm >cd /opt/mqm/samp/bin/
sauron:mqm >./amqsput INPUT_OUTPUT_Q
Sample AMQSPUT0 start
target queue is INPUT_OUTPUT_Q
test message

Sample AMQSPUT0 end
sauron:mqm >./amqsget INPUT_OUTPUT_Q
Sample AMQSGET0 start
message <test message>
no more messages
Sample AMQSGET0 end

Result: SUCCESSFUL communication

- t20ora user (the user who I am trying to run this action under)

sauron:t20ora >./amqsput INPUT_OUTPUT_Q
Sample AMQSPUT0 start
MQCONN ended with reason code 2035
sauron:t20ora >./amqsget INPUT_OUTPUT_Q
Sample AMQSGET0 start
MQCONN ended with reason code 2035

Result: FAILURE

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- Associated information

User groups assigned:

It seems to be necessary to be a member of the 'mqm' group, in order to be able to use the MQ Series install, so....

- Groups assigned to 'mqm' user:

sauron:t20ora >id -a mqm
uid=1055(mqm) gid=101(mqm) groups=101(mqm)

- Groups assinged to 't20ora' user:

sauron:t20ora >id -a t20ora
uid=1050(t20ora) gid=101(mqm) groups=108(tlm),101(mqm)


Performing the authority command for MQ Series Queue and Queue manager:

In order to ensure that the necessary permissions & privileges are assigned to the Queue Manager & Queue, the following command is performed as the 'mqm' user

As mqm user:

sauron:mqm > setmqaut -m QM_STLMQI -t qmgr -g mqm +all
The setmqaut command completed successfully.
sauron:mqm > setmqaut -m QM_STLMQI -n INPUT_OUTPUT_Q -t q -g mqm +all
The setmqaut command completed successfully.

Trying to run the same command as t20ora user:

sauron:t20ora > setmqaut -m QM_STLMQI -t qmgr -g mqm +all
AMQ7077: You are not authorized to perform the requested operation.
sauron:t20ora >setmqaut -m QM_STLMQI -n INPUT_OUTPUT_Q -t q -g mqm +all
AMQ7077: You are not authorized to perform the requested operation.

Showing those Queue & Queue Manager permissions, using the 'dspmqaut' command (again, as both the 'mqm' and 't20ora' user) gives the following:

As mqm user:

sauron:mqm >dspmqaut -m QM_STLMQI -t qmgr -g mqm
Entity mqm has the following authorizations for object QM_STLMQI:
        inq
        set
        connect
        altusr
        crt
        dlt
        chg
        dsp
        setid
        setall

sauron:mqm >dspmqaut -m QM_STLMQI -n INPUT_OUTPUT_Q -t q -g mqm
Entity mqm has the following authorizations for object INPUT_OUTPUT_Q:
        get
        browse
        put
        inq
        set
        crt
        dlt
        chg
        dsp
        passid
        passall
        setid
        setall
        clr

As t20ora user:

sauron:t20ora >dspmqaut -m QM_STLMQI -t qmgr -g mqm
AMQ7077: You are not authorized to perform the requested operation.
sauron:t20ora >dspmqaut -m QM_STLMQI -n INPUT_OUTPUT_Q -t q -g mqm
AMQ7077: You are not authorized to perform the requested operation.


Summary:

Given that all the necessary queue & user permissions, and group memberships appear to be in place, please can someone advise whether I have missed anything obvious, and potentially explain why I am experiencing this fundamental MQ problem?

Many thanks in advance,


Sean Dowding.