Error in MATLAB level 2 S-Function registering method

I have found an error evaluating the initialization for MATLAB level 2 S-Function.

 'Error registering method for 'SetInputPortSamplingData' is unknown'

but my internal registry for the block method look like this ....

 block.RegBlockMethod('SetInputPortSamplingData',@SetInputPortSamplingData);

%%set the sampling ot the input ports......................................................................................................
function SetInputPortSamplingData(block,idx,fd)
    block.InputPort(idx).SamplingMode = fd;
for i=1;block.NumoutputPorts
     block.outputPort(i).SamplingMode = fd;
end