"estimateG​eometricTr​ansform" error: expected single or double

I'm trying to create a panorama with many images. I have used the standard Matlab algorithm for this purpose. This algorithm is explained here: http://es.mathworks.com/help/vision/examples/feature-based-panoramic-image-stitching.html

Since I'm sure that my images are one after another, without rotation etc. I want to change the type of the geometric transformation from 'projective' to 'similarity' but, when I do this, I have the following error during execution:

The following error occurred converting from affine2d to projective2d:
Error using projective2d.set.T
Expected T to be one of these types:

single, double

Instead its type was affine2d.

Error in main (line 66)
    tforms(n) = estimateGeometricTransform(matchedPoints, matchedPointsPrev,...

I don't understand what the error is, do I need other type of matching points instead of the given by SURF features?