Forms :: Logon / Logout Screen

I am developing menu.. in that menu having 5 different forms.. these forms are 3 one schema ( i.e X ) and remaining 2 forms are one schema ( i.e Y )..

i am calling x schema

form level trigger on_logoon :
onlogon('a','a@X');

a for Username and x database name and another form in form level trigger on_logon : coding

logout;
logon('b','b@Y');

b for Username and y database name

but the form is not executing and not saving the record's.