pass a value property after showdialog c# wfa

Hello Guys

i'm really happy to see my problem is solve by your helps, thank you

i have a database

1 login form

1 main form

connection is with dataset and automatic query builder

my user has username/password/UserID (not Identity)

in login form i have a code for login and i made a property for that UserID

after valid login i want to show that userID into main form !

but it doesnt pass to main form

my codes here...

this is login form and getting teacheID from database

and this is main form and want to get that teacher id from login form and show it in a label

after these codes label text is = 0