asp.net - gif image file displays red "x" on IE -

to start off, have searched google & (images showing red x's on ie, shows fine in other browsers), tried out suggestions, did not resolve issue.

i trying create transparent image following code shown at: how draw transparent image using system.drawing?. using 3rd party mapping control "simplovation"

however, when run webpage:

how can actual image appear? tried converting rgb, no luck.

based on code in "how draw transparent image using system.drawing" actual image should appear like:

there long list of potential problems here, let's address 3 of them:

• permissions
  imply creating image code. how doing that? if iis worker process, running in user context of application pool account, creating image, create/save location accesible anonymously? (or whatever authentication model is)
• file locked?
  again, since implying creating image code, close file handle properly?
• path.
  image url correct, 100% sure? press f12 on ie , use developer tools determine if type of http error when ie trying request image.