nios-run: waiting for target.......?

Hello,everyone!I made a design following the tutorial in the nios develop
kit and do the pin assignment as the example the factotry supplys.Then I
downloaded to apex board using quartusII .But I cannot download my execute
code to the FPGA .The sdk shell
annouce that waiting for the target.........why?Thanks. 

Have you try to download your hardware configuration to APEX chip
using JTAG first before you download your hardware design to APEX
using UART???

Besides, have you erase the user configuration in flash memory
content??? If i not mistaken...
  e180000
     .
     .
  e1b0000
  r180000

If still waiting for target...., try to press the reset button on the
APEX board then observe what message on Nios SDK Shell....