M4300-52-PoE and S3300-52

Hi, we have purchased 2 x M4300-52-PoE switches to stack with our existing S3300's - sadly we can't do that according to the documentation! Can I use the 10G Ethernet Ports (49/50 respectively on each switch) to cascade the switches together - I've tried using an ethernet cable between the two ports and don't get a link, despite checking port configuration on both switches... any help appreciated. (If I connect any of the 1Gb ports on the M4300 to the 10Gb port on the S3300 I get a link, but obviously, just running at 1Gb). Many thanks, Dave.