Assignment of new lead when inserting via API call

Assignment of new lead when inserting via API call

Could anyone clarify how I would control who a new lead is assigned to when it is inserted via the api insert method? So we would like to assign it to a lead administrator for example and this person would then assign it to the appropriate sales person. I have tried adding the "Lead Owner" field into the xml but as soon as I do this it throws me an error. If I leave this field out, I notice by default it assigns it to the person whose credentials are used when calling the ticket request method ( I assume?). Any help would be appreciated.