Thank you all anyway, but I already discover the problem.
The logical operator AND must belong to the filter. ie, must be between ""

filter = "T1 < '54'" and "T1 > '23'"; //error

filter = "T1 < '54' and T1 > '23'"; //ok

A simple distraction ... sorry!

BUT, now i have other problem:

There is no operator OR!
How can I achieve the same logic on filtering in M-business?

Thanks again.

Fernando Correia.