Error 'Document 1000 0000000001 2014 already assigned' while posting invoice reduction

Hi Gurus,

here is my situation:

I have created sch.agreement,

GR done and posted IR.

Now created credit memo through MIRO to reverse my previous invoice.

then posted IR(consider number as 0000000001) with higher price.

then this invoice was rejected by buyer due to higher price.

now when i am trying to post this invoice through invoice reduction i am getting an error F5-152: 'Document 1000 0000000001 2014 already assigned'.

Please note that here the number range customized as external and user dont want to change it to internal.

So, Please help me to solve this issue ASAP.