SharePoint BDC Model NULL Structure

I crawle database at FAST Search Server for SharePoint 2010. When incremental crawl is running, it is getting the following error for some records. After the first error, SharePoint takes the same errors from every subsequent incremental crawle.

SharePoint Log:

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1A04 Business Connectivity Services Business Data ca7e Verbose Instantiating Type 'System.String'.
04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1A04 Business Connectivity Services Business Data ca7j Verbose Recursively instantiating Type 'System.String' at a nest level of '0'.

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x0580 SharePoint Server Search Connector Framework e64y Verbose Getting the contents of entity instance with ID Microsoft.BusinessData.Runtime.Identity

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1A04 Business Connectivity Services Business Data ca7l Verbose Found primitive default value ''; returning that instead of instantiating at a nest level of '0'.

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1A04 Business Connectivity Services Business Data ca7f Verbose Completely instantiated Type 'System.String'.

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1594 Business Connectivity Services Business Data bix3 Medium Closed connection to Db: FASTDB
04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1594 SharePoint Server Search FilterDaemon fld1 High Fltrdmn: failure reading ACL. Error 0x8004fd11 [fltrdaemon.cxx:2681] d:\office\source\search\native\mssdmn\fltrdaemon.cxx

04/10/2012 18:56:12.21 mssdmn.exe (0x11C8) 0x1594 SharePoint Server Search FilterDaemon e4ye High FLTRDMN: Errorinfo is "LobSystem (External System) returned a null structure which is incompatible with the associated metadata." [fltrsink.cxx:553] d:\office\source\search\native\mssdmn\fltrsink.cxx

After the first error, every incremental crawle takes same Error which is seen the following crawle history log table .

1. Crawle Log:

   
   
   
   
   
   • Crawle Type : Full
   
   
   • Successes     : 284310
   
   
   • Warnings    : 0
   
   
   • Errors          : 0
   
   



2. Crawle Log:

   
   
   
   
   
   • Crawle Type : Incremental
   
   
   • Successes     : 25375
   
   
   • Warnings    : 0
   
   
   • Errors          : 0
   
   



3. Crawle Log:

   
   
   
   
   
   • Crawle Type : Full
   
   
   • Successes     : 20270
   
   
   • Warnings    : 0
   
   
   • Errors          : 70
   
   



4. Crawle Log:

   
   
   
   
   
   • Crawle Type : Incremental
   
   
   • Successes     : 12650
   
   
   • Warnings    : 0
   
   
   • Errors          : 70
   
   



5. Crawle Log:

   
   
   
   
   
   • Crawle Type : Incremental
   
   
   • Successes     : 26450
   
   
   • Warnings    : 0
   
   
   • Errors          : 70
   
   
   
   
   

   it continues like this.

How can i solve this problem.

Thanks for your attention.

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