Mous,
The first step is to make sure that the NI-DAQ driver is installed properly and that your DAQ board (6025E) is working properly.
Then, refer to page 2-6 and 2-7 of the SCXI 1112 User Manual. It gives some troubleshooting help for the error you are receiving.
http://www.ni.com/pdf/manuals/322476a. pdf.
You may also want to try installing the 2 modules separately and install them in different slots to rule out which module or slot is causing a problem.
Hope this helps. Have a great day