htc a50cml flashing problam need help

htc a50cml(2PQ810000) not going ruu mode
when flashing bootloder mode i got error



Starting flash process...
target rom version: 1.33.720.1
found large-zip header, file count: 7
processing file 1/7...
Process Process-1:
Traceback (most recent call last):
File "C:\Python34\lib\multiprocessing\process.py", line 254, in _bootstrap
File "C:\Python34\lib\multiprocessing\process.py", line 93, in run
File "E:\largezip\htc_fastboot\htc_flashzip.py", line 207, in _do_extract
File "E:\largezip\htc_fastboot\largezip.py", line 61, in extract
OSError: [Errno 22] Invalid argument
sending 'zip' (94541 KB)...
OKAY [ 3.055s]
writing 'zip'...
Error: Not allowed. Probably phone is not in RUU mode. Please switch to RUU mode and try again
)
finished. total time: 3.055s
Flash process completed.
Flash not successfull, reboot will not be done
when enter ruu mode then restart on come in to bootloder mode


Rebooting to RUU...
Operation finished
Phone DISconnected
Phone connected [LC5CXB804994] *** Fastboot mode