Summary:

A user can not create a new company, person etc. on a tablet.

Symptoms:

This was occuring when a user's "Home Territory " was set to anything other than Worldwide.

Resolution / Workaround:

A workaound is to use the desktop theme for a tablet.
This can be set in My CRM -> Preferences and set the field "Default Tablet version" to Desktop Version.

Status:

This issue has been escalated to our development team and will be resolved in a future Sage CRM patch. 

More information:

This is an issue in Sage CRM 7.1.
This issue was not an issue in Sage CRM 7.2 but this issue occurs again in 7.2e onwards.
This is not an issue in Sage CRM 7.3 GA.