Referal interest rate to Fix

Dear Expert ,

I have created 62A interest rate instument,and i am fixing the refereal interest rate ( LIBOR) by TJ05/Ti10.

Now we have two cash flow, one is for 31.03.2015 and 30.06.2015.But the client want to fix only one  interest rate for 30.06.2015.

And client don't want to fix the interest rate 31.03,2015 as they don't want to post the transection.Now my problem is system is

not allowing me to fix the interest rate for 30.06.2015,before 31.03.2015.

Please suggest some idea how to resolve this.

Regards,

Samar