Amos vs lisrel on scalar invariance


I´m used to work to Lisrel and when I have to test scalar invariance I fix the matrix "tau X" equal across by groups. I´m trying in Amos but when I check the intercept the all model are undetermined. I have made a lot of test but just I click the intercept in the output panel the model don´t run.
How Can I do to test scalar invariance ?
Why I have just clicked on "Intercept", the model does not work ?
Help !!!