Doing everything by POST only

Hi everyone I am working on one single website which seems pretty simple and straightforward but I have no idea why my script is not working:/

The register is just 3 POST request to 3 link

1st POST request
modify url=www.test.com/generate/verificationCode
post data=url=&account=%your e-mail%&useType=0

after this request, the email should receive a verification code in below format.

驗證碼： 723326 ，使用了郵件驗證功能。【本驗證碼將在本次使用後自動失效，請勿把驗證碼告知他人】

2nd POST request
modify url=www.test.com/v1/checkCode
post data=account=%your e-mail%&code=%email_code% (723326 in this case)

After this request, the email should be deemed as verified on the server side.

3rd POST request
modify url=www.test.com/v1/auth/register
post data=username=%your e-mail%&password=%password%&email=%your e-mail%

This request is the final registration.

Now I am stuck with that SER cannot grab the code for 2nd step.
It seems it doesn't even log into the email to check

Any help would be appreciated.

[setup]
enabled=1
default checked=0

engine type=My Engine
description=Developed for a Project
dofollow=0
anchor text=1
creates own page=1
uses pages=0

fixed url= www.test.com
add keyword to search=0
use blog search=0
extract keywords=0

skip ext links on=0
skip content on=0
skip url content on=0

extract from email=email_code

;-------------------------------------------------------------------------
;the variables we have to define for this engine (if not already defined before)
;name, keyword, url, e-mail are already defined by default

;the form variables and how to fill them



[Password]
type=password
must be filled=1
hint=A password used for websites that need an account. Use numbers and letters only.
static=1

[Your E-Mail]
type=email

[email_code]
type=extract
front=： 
back=，
remove html=0

;---------------------------------------------------------------------------  
;the form variables and how to fill them

[REGISTER_STEP1]
just download=1
verify submission=0
verify by=extractemail
verify interval=1
first verify=0
verify timeout=140

[REGISTER_STEP2]
modify url=www.test.com/generate/verificationCode
post data=&account=%your e-mail%&useType=0
just download=1

[REGISTER_STEP3]
modify url=www.test.com/v1/checkCode
post data=account=%your e-mail%&code=%email_code%
just download=1

[REGISTER_STEP4]
modify url=www.test.com/v1/auth/register
post data=username=%your e-mail%&password=%password%&email=%your e-mail%
just download=1