Soundcraft 200SR: routing channel to stereo outs?

[ZombieMorg]

Might be a silly question, but is there a button on the group masters to route them to the stereo output?

[headbucket]

Thanks for your response- I'll take whatever pointers or suggestions. Buttons above the 4 group masters are "RET;" below (above faders) are "SUB" and "PFL." Getting signal to headphones when assigned to either 1-2 or 3-4, and when in PFL on individual channels, but no output to power amp. Output cables are female XLR (board outs) to 1/4" males (into amp). Wondering if there's an issue with how sub / stereo outs vs. XLR's are wired.