Make sure you are in the USB or LSB mode on the radio for TX using the soundcard interface. You may have to zero beat and then offset for 700hz plus or minus.
I could be way off base but my FT-847 only works on the data jacks in USB, LSB, AM, and FM. In CW it does nothing. A keyed transmitter in the CW mode should send a solid CW tone?
Try plugging a set of headphones into the soundcard to make sure you have audio at the output going to the radio as well. If there is no audio it is the same as a deadkey (no mic attached or turned off) and would put out zero forward power in SSB.
Best of luck.
Could we with ink the ocean fill and were the skies of parchment made, Were every stalk on earth a quill and every man a scribe by trade. To write the love of God above would drain the oceans dry, nor could the scroll contain the whole though stretched from sky to sky.