vbscript problems in production

Good day, I have a serious problem, I am reviewing a page made in classic asp and vb which has included VBSCRIPT, the same stopped working suddenly and I have looked for how to fix it and does not want to work, the error it gives is

  

Server Error: 500 - Internal Server error

I have reviewed:

• Changing the browser version of the Edge or IE11 to IE10 continues with the same error with F12

• Add this code <meta http-equiv="x-ua-compatible" content="IE=10">

The vbscript code is as follows.

<script language="vbscript" type="text/vbscript">
dim StrPlan
StrPlan =   "<table border=""0"" cellpadding=""0"" cellspacing=""0"" width=""505"">"
StrPlan = StrPlan & "<tr>"
StrPlan = StrPlan & "<td valign=""middle"" width=""503"">"
StrPlan = StrPlan & "&nbsp;"

StrPlan = StrPlan & "<p><font face=""Arial""><b>Planes</b></font></p>"
StrPlan = StrPlan & "<table border=""0"" cellpadding=""0"" cellspacing=""0"" width=""100%"">"
StrPlan = StrPlan & "<%Call STRPlanesDeRegistroActual()%>"
StrPlan = StrPlan & "</table>"
StrPlan = StrPlan & "</td>"
StrPlan = StrPlan & "</tr>"
StrPlan = StrPlan & "</table>"

Sub DalePlanes()
    document.all.FontMenuPlan.size = "2"
    document.all.FontMenuDep.size = "1"
    document.all.FontMenuRec.size = "1"
    document.all.FontMenuPrimas.size = "1"
    <% if session("ENTE") = 2 then %>
        document.all.FontMenuCiaSeg.size = "1"
        document.all.FontObservaciones.size = "1"
    <% end if %>
    document.all.Muestra.innerhtml = StrPlan
end sub

What could be the error?

Thankful in advance

EDITION

Activating options to display more errors in both IIS and IE shows the following message.

  

Microsoft VBScript compilation error '800a0409'

     

Unterminated string constant

     

/ - / - / LimitData.asp, line 101

     

StrPlan = StrPlan & "<% Call STRPRegistration PlansActual ()