No rendered image from Chartservlet

Hello forum ,

We have a irpt file containing a <img> tag which src contains a CHARTSERVLET call .  It used to work fine,  but now it does not show the chart .  ¿ What might be the cause ? .

Thanks in advance,

Note 1:

We are running a 12.2.3 BUILD 167 SP5 MII plataform

Note 2 ( part of the javscript code ) :

var GrafProduccion = document.getElementById("GrafProduccion");

GrafProduccion.src="/XMII/ChartServlet?StartDate=" + fechaHaceUnMes + "&EndDate=" + fechaGraf + "&XAxisMajorTickCount=" + TickCount  + "&Title=Produccion&Width=400&QueryTemplate=ReporteDiarioLPG%2FQueries%2FGraficaProduccionXacute&DisplayTemplate=ReporteDiarioLPG%2FDisplays%2FGraficaProduccion&Content-Type=image%2Fpng&Height=200";

Note 3 ( somewhere inside a table tag ) : 

<img id = "GrafProduccion" width="100%"></img>