Creatin N to N relationship

Hi,

I’m trying to create an N to N relationship form, but is not possible for me. I have 3 tables

AT_Campania
[INDENT]IDCampania[/INDENT]

XT_Campania_Maquina
[INDENT]IDCampania[/INDENT]
[INDENT]IDMaquina[/INDENT]

AT_Maquina
[INDENT]IDMaquina[/INDENT]

I tried to create en N-N Relationshipo from ScriptCase naming the field as XT_Campania_Maquina and the next steps how the videos explains. All the time I got the same error : Link Table table / fields missing:xt_campania_maquina.

Could someone help me? Best Regards