Back-up your wagmp_map_1.php file in case you need to revert to it.
In your wagmp_map_1.php file (it may have a different number on the end) find the line of code (about line 115):
var map = new GMap2(document.getElementById('wagmp_map_1'));
Place the cursor at the end of the line and press the return key to create a new line, and add this line:
Edit (add): For a hybrid map it would be: