I'll bet that you have a rasterized image that's been embedded in an SVG file.
When Blender imports an SVG, it takes the spline curves that define the vector graphic in the file, and convert them to splines (or a mesh) to define it in 3D. Unfortunately, you can have a rasterized (pixel-based, instead of vector-based) image embedded in an SVG project. That image will not be imported by Blender because it doesn't have any splines or vectors.
You can check this by opening the file in an SVG editor (like Inkscape or Illustrator) and trying to select the vectors that define the borders. If you can't select any edges, then zoom in super close and see if you start seeing pixels. If you start seeing pixels, then it's rasterized, not vectorized.
If that's actually the case, then this IS a duplicate of Why can't I import a SVG file from Adobe Illustrator or Inkscape?
I hope that helps!