From the photo I can't be sure that pins 13 and 14 are both low - address inputs A3 and A2 respectively, these need to be low to select the correct set of inputs (in particular pin 14 has a red wire not a blue one, which implies you are selecting channels 4/5/6 rather than 0/1/2. The signal wires are going into pins 9,8,7 (channels 0,1,2).
The leakage current specification is upto 0.8uA for switches in the off state, plenty large enough to explain your readings.