time step jumbing

Hello,
When i print the time steps of the a grib file using the NCL , i found some
jumping in the time steps as the following

(0) this is forcsast 0 0
(1) this is forcsast 0 3
(2) this is forcsast 0 6
(3) this is forcsast 0 9
(4) this is forcsast 0 12
(5) this is forcsast 0 15
(6) this is forcsast 0 18
(7) this is forcsast 0 21
(8) this is forcsast 0 24
(9) this is forcsast 0 27
(10) this is forcsast 0 30
(11) this is forcsast 0 33
(12) this is forcsast 0 36
(13) this is forcsast 0 39
(14) this is forcsast 0 42
(15) this is forcsast 0 45
(16) this is forcsast 0 48
(17) this is forcsast 0 51
(18) this is forcsast 0 54
(19) this is forcsast 0 57
(20) this is forcsast 0 60
(21) this is forcsast 0 63
(22) this is forcsast 0 66
(23) this is forcsast 0 69
(24) this is forcsast 0 72
(25) this is forcsast 0 75
(26) this is forcsast 0 78
(27) this is forcsast 0 81
(28) this is forcsast 0 84
(29) this is forcsast 0 87
(30) this is forcsast 0 90
(31) this is forcsast 0 93
(32) this is forcsast 0 96
(33) this is forcsast 0 99
(34) this is forcsast 0 126
(35) this is forcsast 0 132
(36) this is forcsast 0 135
(37) this is forcsast 0 138
(38) this is forcsast 0 141
(39) this is forcsast 0 144
(40) this is forcsast 0 147
(41) this is forcsast 0 150
(42) this is forcsast 0 153
(43) this is forcsast 0 156

the file has a time step each 3 hours but after forecast hours 99 , it jump
directly to 126 and this is not true
also there is other jump after 126 , it jumps directly to 132.
i make wgrib -v for the grib file ,and i found the all time steps exist
correctly , no jump exists .
i have attached the output of the wgrib -v for the grib file ,also i have
attached the ncl file code
thanks in advance

-- 
===============
Ahmed Lasheen
Junior researcher at Cairo Numerical Weather Prediction Center (CNWPC)
Egyptian Meteorological Authority(EMA)
Cairo,Egypt
===============

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