Hi All. I have a demand site (a branch) with time horizon ( 1962-2020) ,
1: from 1962-2010 with the same Monthly Variation
2: from 2011-2020 with a different Monthly Variation.
when i input all data above ( with horizon 1962-2020).WEAP can not run with whole time from 1962-2020. However when i divide time horizon into two periods ( 1962- 2010 and 2011-2020), Weap can run with each period.

my question: how to run with the whole time horizon 1962-2020 with different Monthly Variation for each period? please help me.

Using the "If" function, you can specify a different monthly variation for different years. For example, this expression will use one variation for years on or before 2010, and another for years 2011 and later:

If(Year <= 2010,
MonthlyValues( Jan, 7.06, Feb, 7.31, Mar, 7.85, Apr, 8.41, May, 8.89, Jun, 9.64, Jul, 9.81, Aug, 9.77, Sep, 8.84, Oct, 8.01, Nov, 7.37, Dec, 7.04 ),
MonthlyValues( Jan, 0, Feb, 0, Mar, 5.97, Apr, 10, May, 15.3, Jun, 17.8, Jul, 20, Aug, 17.1, Sep, 10, Oct, 3.83, Nov, 0, Dec, 0 ))

Jack