GR/IR clearing all the documents are not clearing

Dear Experts,

In ob74 i have the following setings for my GR IR clearing a/c

EBELN

EBELP

GSBER

VBUND

ZUONR

My client is using F.13 clearing function. But in that some entries are not clearing.

Example of that

Assignment Docment no. TYPE Pk Doc date Psng Date Amount in DC Cur Amt in Loc Cur Lcu Reference

450002593900002 5000004774 WE 50 26.5.2009 8.6.2009 2785.59- SAR 2785.59- sar

450002593900002 5100006581 RE 40 07.11.2009 6.12.2009 2785.89- SAR 2785.59- sar

Here assignemnt field is same and amount in DC is also same but can you please let me know the why it is not cleared.

Thanks

Bhaskar