Task weights functionality problem

Hello,
We were using erpnext for our project with a lot of tasks with task weights but after raw 45 we are having problem. Although we are 100% sure that the sum of all task weights is equal to 1 but it keep giving us a message "Total of all weights should be 1. Please adjust weights of all project tasks accordingly. "
But when we delet the last raw and put the weight to the previous raw it works just fine. So please any one solve this for us urgently.
Thanks

Duplicate https://discuss.erpnext.com/t/task-weight-functionality-problem/36423