Relation without dropdown

Relation without dropdown

Hi,
I have this code

y  =  Matr_cula_Consular  [(matr_num == input.Matr_cula && Nome_completo_m_e == input.Mae)];
if (count(Matr_cula_Consular[matr_num == input.Matr_cula])  >  0)
{
    input.Nome = y.Nome;
    input.Sobrenome = y.Sobrenome;
    input.Email = y.Email_pessoal;
    input.Telefone = y.Celular.toString();
    input.Cidade = y.Cidade_Res_It;
    show Nome;
    show Sobrenome;
    show Email;
    show Cidade;
    show Telefone;
    show Argumento;
    show Comentario;
    disable Nome;
    disable Sobrenome;
    disable Email;
    disable Cidade;
    disable Telefone;
}

That with a Matr_cula and Mae dropdown field run very well. But I need change dropdown in Line field and when I try to save the script I have this message:
Error in statement at line number 1
The Left expression is of type BIGINT and the right expression is of type STRING And the operator == is not valid here.

Any suggestion?
Thanks.
Mic