Introduction to Programming Using Visual Basic 2005, An (6th Edition)

In VB2005, every parameter in the header of a Sub or Function procedure must explicitly be declared as ByVal or ByRef. If neither is stated, VB2005 will automatically insert ByVal before the parameter name.

In a VB2005 call statement, the name of the Sub procedure must be followed with parentheses even if there are no arguments.