Is there a maximum number of different marker styles in google static maps api?

I am trying to create aseries of maps with markers. I have experienced, t开发者_开发问答hat when there is 5 or more markers shown at the same time, one of the markers are not rendered properly.

Here is an example.

As far as I can see, the icon url is correct, and if i remove one of the markers, it is shown properly..

What is wrong?

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From the Static Maps API developer reference:

"The Static Maps service allows up to five unique custom icons per request. Note that each of these unique icons may be used multiple times within the static map."

http://code.google.com/apis/maps/documentation/staticmaps/