Filter function in slicer

[Cognos8]

I am receiving date prompt in format of 2010-01-01 and Sep 01, 2015. Whatever format i receive
this needs to be converted to YYYYMMDD and filter with database data.

Version : Cognos 10.2.2 and Netezza
Dynamic cubes


Scenario is , i have two prompts and need to include slicer (ex: date between ?fromdate? and ?todate?). Before this i want to convert the prompt date format to YYYYMMDD and using filter function filter the data from slicer. Below code is working fine in oracle but not with Netezza.
Please throw some light on this. Thanks

filter( [WANE].[FISCAL].[FISCAL].[DAY],
[WANE].[FISCAL].[FISCAL].[DAY].[DAY - Key] between  #substitute('-','',substitute('-','',prompt('P1','Date')))# and  #substitute('-','',substitute('-','',prompt('P2','Date')))#
)