error in adding new feild in the bank account

i create a feild as last checkused in bank account master.

and have table relation with no.series line . last no used.

I drag column in Bank Account form.

when i selecting the following i am getting follwoing error.

The following field must be included in the table’s primary key Field: Last No. used Table: No seires line

i created on more column as seriescode in bank account, it is picking the series code properly.

can some body help me

The error is because you can define the Table relation to field which is part of Primary key of the table.

In your case Last No. used field is not a part of no.series line table’s primary key

i am using this for cheque no series. i already pickup on value for series code. and now i want to dispay the last no from the series. can u pls help me on this

You already have “Last Check No.” field in the bank account master card.

I am using no. series code for the same, i know there is last check no in bank master. but it is used for coputerised check printing. i want for manual , system should display the last check no utilised.