error using createMask on imellipse object

Hi,

I created a circle (using imellipse) over a plot (imagesc, uint16 matrix).

the code is:

Circ81 = imellipseimellipse(handles.sub1,[(handles.sub1.XLim(2)/2)-r1 handles.sub1.YLim(2)/2-r1 2*r1 2*r1]);

setFixedAspectRatioMode(Circ81,1)
setColor(Circ81,[1 0 0])
Posi = getPosition(Circ81);
ddW81 = createMask(Circ81);

I use this kind of code several times, no problems. For a particular imagesc plot I am getting the following erro:

Error using poly2mask

Expected input number 1, X, to be one of these types: double

Instead its type was single.

Error in poly2mask (line 38)

validateattributes(x,{'double'},{},mfilename,'X',1);

Error in imroi/createMask (line 261)

BW = poly2mask(roix,roiy,m,n);

Error in ACR_test_bmdc>Roi81f (line 6575)

ddW81 = createMask(Circ81);

Error while evaluating UIControl Callback.

I noticed that the BW = poly2mask(roix,roiy,m,n); roix and roiy inside the imroi.m function are indeed single precision, as the error says and a simple double(roix) solves the problem. However, I am not happy to modify an original Matlab function (a read only one) without understanding of what is happening.

Thank you!