Issue in counter based preventive maintenance

Hi,

I am facing following issue in counter based preventive maintenance...

I have created a measuring counter for a equipment as below. then created a maintenance plan (single cycle) for the equipment with interval of 1000 hr for the preventive maintenance. I entered a measuring document with reading as 1100 HR. Now when I schedule the maintenance plan, system creating order for the first call on 07.05.2015. but why system creating subsequent calls ( from 06.08.2015 and so on ) as shown in the third screen shot when there are no measuring documents after 1100 HRs???. Please help

Thanks

Kumar