Label limits of a static Google map

Question

In my static Google Maps, when I put a label in my markers, the counter is displayed for just 7 markers.

Is there a limit? If yes, how can I break this limit?

You can see it here : http://maps.googleapis.com/maps/api/staticmap?center=Bordeaux,FR&zoom=13&size=600x640&maptype=roadmap&markers=color:blue|label:1|44.8424,-0.578465&markers=color:blue|label:2|44.7991,-0.662782&markers=color:blue|label:3|44.8254,-0.557401&markers=color:blue|label:4|44.8398,-0.571568&markers=color:blue|label:5|44.8583,-0.567102&markers=color:blue|label:6|44.8415,-0.582481&markers=color:blue|label:7|44.832,-0.596226&markers=color:blue|label:8|44.8515,-0.573702&markers=color:blue|label:9|44.9683,-0.63589&markers=color:blue|label:10|44.853,-0.572936&markers=color:blue|label:11|44.8625,-0.620819&markers=color:blue|label:12|44.8278,-0.586139&markers=color:blue|label:13|44.8281,-0.552797&markers=color:blue|label:14|44.8894,-0.563988&markers=color:blue|label:15|44.8407,-0.558983&sensor=false

Answer 1

According to Static Maps API V2 Developer Guide (emphasis mine):

label: (optional) specifies a single uppercase alphanumeric character from the set {A-Z, 0-9}. (The requirement for uppercase characters is new to this version of the API.) Note that default and mid sized markers are the only markers capable of displaying an alphanumeric-character parameter. tiny and small markers are not capable of displaying an alphanumeric-character.

You are using more than a single character in some of your labels, which is why it isn't working.

After numbers 1-9, you can use the letters A-Z like this (I decreased zoom a bit because not all markers were visible).