Standard Deviation Measure showing 'nan' as value

Hi,

We are trying to export standard deviation once promotion forecast is generated in RDF. As per base rdf to rms export script, Std deviation measure is appcumint12xb (measure as per our forecast level defined in config). When we export the forecast measure and std deviation measure we are getting values like below:

For item 100085, std deviation is showing weird values.

Day,item.store,promoforecast, stddeviation

20150423,100085,104,0,-9.2233720368548e+14    <--- Incorrect values

20150430,100085,104,0,-9.2233720368548e+14    <---

20150507,100085,104,0,-9.2233720368548e+14    <---

20150423,3016505,104,0,0.2337

20150430,3016505,104,0,0.3305

20150507,3016505,104,0,0.4048

When we do print measure of appcumint12xb below are the values showing up:

printArray -array .appcumint12xb%1|head
navalue                 :    0

(wk17_2015 100085 104 info):    nan