CRM 2011 Form Ribbon Bar Disappeared

Hello Experts,

I have found one strange issue with CRM 2011. I have two CRM instance on different server but pointing to same sql database. So one is acting as a virtual server. I have an entity form that has some JavaScript functions and two buttons. We have written custom rule to enable or disable button. It works perfectly on one server while on another server ribbon bar disappeared. We are on rollup 15.

Do you think it is because of custom button? If yes, then why it shows the ribbon bar on first CRM?

Can somebody suggest any solution for this?

Thanks!