GLM Label - Decreased Sequential Numbering

Dear Experts,

This is regardign GLM Label.

we have a sequence number on label. now business wants to print the label reverse which means from 6 to 1. So increment giving as -1 as shown below,

but getting below error - Specify Positive Values Only

can anybody guide how to overcome this issue? as it is very common and simple thing business is asking...

Kindly advise..

Thanking You,

Regards

Ravi