qbasic.hlp (Topic list)
Cannot cross procedure boundary
During debugging, you used the Set Next Statement command to
specify a statement that is in a procedure other than
the one where program execution is suspended. In this case,
QBasic ignores the Set Next Statement command.
 
To continue debugging, move the suspended procedure into the
View window. You can then use the Set Next Statement command
to start running from any statement in that procedure.