The X++ debugger works only for users who are in the 'Microsoft Dynamics AX debugging users' local group of windowS

1. From the Start menu, point to All Programs, click Administrative Tools, and then click Services. 
2. In Services, right-click the Microsoft Dynamics AX Object Server service and then click Properties. 
3. In the Properties window, on the Log On tab, the AOS service account is specified in the This account field. 

To add the AOS service account to the debug group 

1. From the Start menu, point to All Programs, click Administrative Tools, click Computer Management, and then click Local Users and Groups. 
2. In Local Users and Groups, double-click Groups, right-click Microsoft Dynamics AX Debugging Users and click Add to Group. 
3. In the Properties window, click Add and add the AOS service account to the group. 
4. Restart the machine