Error in campaign

I am trying to get contents of advertisement from commerce server 2002 bizdesk to my asp.net application using content selector.i Have created ad campaign in bizdesk
i have made web configuration accordingly
Refering Step 6: Implementing Content Selector Code
My code is as below.
I AM NOT TARGETING ANY SPECIFIC USER


CommerceContext ctx = CommerceContext.Current;

ctx.TargetingSystem.TargetingContextProfile["Pagegroup"].Value="ALL";
ContentSelector csoAd = ctx.TargetingSystem.SelectionContexts["advertising"].GetSelector();
csoAd.TraceMode = true;
csoAd.ItemsRequested = 1;
//Get some content using CS2002 Content Selection Framework
StringCollection adpayload = csoAd.GetContent();


on running i am getting below error

Component Execution failed for component[0x0] hr: 0x80004005 ProgID: Commerce.CSFInitPipeline.1 The CacheManager failed to populate the cache due to a previous error. The cache load will not be attempted again until the RetryInterval has elapsed or until RefreshCache is called. Previous error: "Commerce.CSFLoadAdvertisements: Invalid expression argument value, or impossible conversion. (Expression ID = '⏏ᇦ騯ﯗꀖ爵྄갧譕菬⓬噓疋謈圆䶉跬㍑棿䛐撐襖ﱽ綉觸읦�ჿ삅贏胈')"

StringCollection adpayload = csoAd.GetContent(); line is causing error.

can anybody help me to solve.
Any help will be appreciated in Advance

Regards
Habeeba