Ensure connection string has been initialized

 Hi everyone.
I am getting this error:
"Connection String has not been initialized"
To give you some background, I have the following:
Page.aspx

Page.aspx.vb
MyClass.vb - Contains business logic, and SQL commands that are executed.
DataAccessClass.vb - Class that handles all database related operations
 
Basically, when I invoke a Public Shared function from MyClass.vb, sometimes it would work.  On other occassions, it just would not work.
I am getting the connection string value  from a webservice.  When my page loads, the web service is checked and the connection string value is retrieved.
MyClass.vb will then invoke a function which would run an SQL command, use the data access class and get the value back to MyClass.
In my data access, each database operation, I already placed a check whether the connection string is valid (
i.e.
If IsNothing(ConnectionS ...