SAPWL_WORKLOAD_GET_STATISTIC don't return data

Hi,

I tried using the function module

SAPWL_WORKLOAD_GET_STATISTIC
   PERIODTYPE = D
   STARTDATE = 20150423
   ONLY_APPLICATION_STATISTIC = X
   INSTANCE = TOTAL

I tested all the export table but always  this function module don't return data

Thank you in advance for the Help.

akrem