Problems with ajax calls

I have some problems with ajax calls with some components and module, they just load blank pages instead of correctly retrieving the information

I have the problems with virtuemart and bixie VM chronoform. It is working very well with the desktop version, but not with any of the mobile version

Any clue ?

Alterna, did you ever resolve this issue with ajax? I'm having similar problems. 

Any suggestions much appreciated!

Please, post URL of the page demonstrating the issue. Otherwise unlikely there is a way to fix the issue.