Subdomain problems

I have the contact form 7 installed on my WordPress main site (ie: http://www.mysite.com). Then i created a subdomain that calls a page from my main WordPress site (ie: http://mysubdomain.xxx.com).
The problem is that the same CF7 that i have on my main site doesn’t work on my subdomain. I think that on the Subdomain it calls the submission page by using a relative path instead of using an absolute but i don;’t know how to solve.
Can you pls help me?
Thanks in advance
bye
Marco

https://wordpress.org/plugins/contact-form-7/