matlab error - time series commands

Hi, I'm trying to generate a lagged data set. I tried the function below and I get the error that follows.

>> testv=lagts(maxtemp,1); Undefined function 'lagts' for input arguments of type 'double'.

Incidentally, I get the same error when I tried using XLAG. I uploaded the data straight from excel, did not create it in matlab. any suggestions please?

Thanks Chet