Request for the permission of type 'System.Security.Permissions.FileIOPermission, msc

I am using Itext sharp to create a pdf. I am adding an image and I keep getting this error

Request for the permission of type 'System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

it is this bit of code that is causing this

Code:

---

.... 
 
 string imagepath = "C:\\BMSApplicationFiles\\PDFImages\\bullfrogWeb.gif"; 
 
 //add the Image to the DOC 
  Image bullfrogImage = Image.GetInstance(imagepath); 
  bullfrogImage.ScalePercent(60f); 
  bullfrogImage.SetAbsolutePosition(10, doc.PageSize.Height - 36); 
  doc.Add(bullfrogImage);

---

If i comment this out, the PDF builds and no errors are thrown (there is just no image)

I don't understand cause all i am trying to do is read a file.

The directory does have full permission granted to IISUser

Any ideas why I am still geting this permissions error?
Thank you