ipMonitor first tests that it can communicate with the informix server before asking for the credential. The QA ADO monitor wizard expects certain error codes to be returned before going to the next step. It is possible your setup or a newer version of informix is returning something ipMonitor is not expecting.
In this case you can try choosing the type as "Other" in the QA ADO Monitor setup and manually configure the monitor. To help you with filling out the Database connection string fields, you can open the UDL data source file you have already tested with inside notepad to see the connection string. Then you can copy/paste the values into ipMonitor and create the monitor.
Thank you very much.I opened my UDL in notepad, selected 'Other' when adding the ADO and copied the various connection properties and it work perfectly.
Interestingly the server I was trying to connect to was 64bit Informix 11.50 FC2 which is very new so this may have been the cause. Thanks again for the quick response.