How can i solve this problem

Hi

I have one VB.NET application and i declare a thread as a
public variable in the form.I want to declare this same
thread as a public variable according to my flexibility,so
i have to declare like this and removed in the declaration
in the form.
The thread was started with the function.In that function
i have a database connection and i have fill a dataset in
that function.While at the time of filling dataset it
gives error like that:
"The connectionstring property has not been intialized."

The same code was worked without giving errors if i put
the global declaration of a thread in the form also.
But if i removed this thread declaration in form i got an
error.
How should i solve this problem.
I want to use the thread declaration in the module only.
If any one knows the solution please give me the reply it
is very urgent to me.Thanks in advance.

Mamatha