Cannot deploy SimpleUI template app to my phone

[XiaoGuo, Liu]

I created the SimpleUI QML application, and it cannot be deployed to the phone. However, the previously created QML apps can be deployed without any problems. The errors are show as below. This problem can be consistently duplicated!

Status: Waiting in queue
Status: Starting
Status: Finished
Transaction: Installing files
Status: Waiting in queue
Status: Waiting for authentication
Status: Waiting in queue
Status: Starting
Status: Finished
Results:
Installed com.ubuntu.developer.liu-xiao-guo.SimpleUI1-0.1.all (installed:click,removable=1,app_name=SimpleUI1)
Application installed, executing

** (process:28344): WARNING **: Unable to find keyfile for application 'com.ubuntu.developer.liu-xiao-guo.SimpleUI1_SimpleUI1_0.1'
Traceback (most recent call last):
  File "./qtc_device_applaunch.py", line 211, in <module>
    logTailProc = subprocess.Popen(['sh','-c','while ! tail -n 0 -f '+UAL.application_log_path(app_id) +' 2>/dev/null ; do sleep 1 ; done'],stdout=subprocess.PIPE)
TypeError: Can't convert 'NoneType' object to str implicitly

[XiaoGuo, Liu (liu-xiao-guo)]

I have updated the chroot, and the problem is the same! Could you please help this as soon as possible since I need to use the tool. This is tested on trusty!

[XiaoGuo, Liu (liu-xiao-guo)]

The problem happens on trusty.