The data in the first column of SigData is the time (or time step) info. It must be incremental (or non-descreasing).
Based on your code, when there is more than one cycle, the time step is constructed as 0.001 to 3, and then 0.001 to 3 again and then 0.001 to 3 again.
Change this line
SigData(aux,1) = t
to SigData(aux,1) = t+(i-1)*round(T,3)