You're trying to jump to the array where the addresses are stored, which doesn't make sense. You need to load the target address from the table before the jr
instruction:
sll $s0,$s0,2 #$s0=index*4
la $t0,jTable #$t0=base address of the jump table
add $s0,$s0,$t0 #$s0+$t0 = actual address of jump label
lw $s0,($s0) # <-- load target address
jr $s0 #jump to label