loadVariablesNum doesn't work sometimes?

Sometimes my loadVariablesNum code doesn’t seem to work. Usually it works on high-speed and usually it doesn’t work on dial-up.

Why? What can I do to make it always work?

Here’s the code:

On successive frames in the first loop that loops quite a few times are:

loadVariablesNum(_root.text_file, 1);
_level1.pass_dynamic_text = _level1.dynamic_text;
_root.save_dynamic_text = _level1.pass_dynamic_text;
_level0.displaytext = _root.save_dynamic_text;

On successive frames in the final loop that loops forever are:

_level1.pass_dynamic_text = _level1.dynamic_text;
_root.save_dynamic_text = _level1.pass_dynamic_text;
_level0.displaytext = _root.save_dynamic_text;

So what could cause the text to not make it to the screen sometimes?