Error importing image. Unsupported image format

Hi,

I'm using a Image Field to send a gif n base64 to a PDF

when I do a simple test in the designer open the GBES1004.pdf and drag the image bad.gif into GeDocImage returns the error:

Hint: ImageStore loadEmbedded method failed. Key was [form[0].#subform[0].GeDocImg[0]].
   Error importing image. Unsupported image format.
   XFAImageService: Image cannot be resolved for node: GeDocImg.

I do the same test with the image good.gif the preview pdf works without any problem

Otherwise if i convert the bad.gif in jpeg works well

Can anybody help with this issue?

thnaks in advanced