the reason i asked to see the php page is that you are not giving the entire recordset code. You are not providing the code that sets the parameters used by the recordset, this porting of the code is crucial to being able to understand the nature of the problem.
I asked further asked for details to clarify how the parameter was configured. Rather than give specifics you just replied that it was configured according to instructions, if that where the case, it would work.
even if it where on a blank page, the details you have provided are not sufficient to answer the question.
even your last question:
"can you help to tell me why it would not have worked with thr OR in it that was generated by data assist?"
does not give me enough information. what is the query you are using now?
I one see one or statement in the previous query, and it should not have an effect on what you are trying to accomplish. the only thing that I can think is that another set of brackets is needed:
WHERE (ClientID = ParamClientID OR ( -1= ParamClientID2 AND ClientID= ParamSessionClientID)) AND clients.ClientUserID = paramUser
but really, your leaving me to guess at what the changes you made where