We have a 6509 with a 4000W power supply, a high speed fan and a s2-pfc2 running catos 8.4.2. The 6748 is being denied power because it is not recognized. We tried another sup engine with ios 12.1(27), it recognized the card but said it was incompatible and denied power. Software Advisor recomends 8.1 or 12.1(26) as the minimum required releases for the card. What else have we not tried? Information has been hard to find as to what sup engine it needs to run, but the Software Advisor accepted our config.