Cheque Number Disappers

Dear Members,

I've made some out going payments in banking module and in payment means i entered the check number also and taken a print out of the outgoing payment.

Now after two days if I see this entry again, the check number got disappeared.

Only for some entris this is happening .

What may be the issue .can anyone help me out.

Your answers will be highly appreciated

Thanks & Regards,

Suresh Kannan