The code:

ILookup tb1 = ControlFactory.CreateLookup();

tb1.AllowedObjectTypes.Add(otc); // otc = 2

tb1.AllowCreateNew = true;

tb1.AllowViewProperties = true;

tb1.LookupStyle = LookupStyles.Single;

tb1.ID = SectionParty_ + id;

This is a situation that requires you to make sure you configure the c360 SDK properly to indicate the URL to your CRM system. In particular, take a look at step 10ii in the following article: http://www.c360.com/Forums/Topic693-40-1.aspx

Both on the same machine but adding the key solved the problem.