agent not receiving work item assigned to him

Dear gurus,

we're using SRM server 550 with SP08. We are using n-step workflow for contract change version. The approvers are being determined by reading from a table. In total there are 8 approvers determined. We then add one more approver manually. Then we do the approval. The approver1 manage to approve the contract successfully. However the problem come when approver2 want to approve, in which the contract not appear in his inbox.

When we check the contract again, we still see the approver as approver2, with slight difference in which there is no information "In approval since xxxx".

Can anyone suggest how can we prevent this to happen? And what can we do if such case happens?

Best regards,

John