Working on daily grid files of NO2 on City scale

Hello I am working on S5-P NO2 datasets for 4 years. I want to process data in its default resolution.

operations= “latitude >= 4.9[degree_north] ; latitude <= 38[degree_north] ;
longitude>= 60 [degree_east]; longitude<=98 [degree_east];tropospheric_NO2_column_number_density_validity>75;
keep(latitude_bounds,longitude_bounds,datetime_start,datetime_length,pressure_bounds,tropospheric_NO2_column_number_density,tropopause_pressure);
derive(datetime_stop {time} [days since 2000-01-01]);
derive(datetime_start {time} [days since 2000-01-01]);
exclude(datetime_length);
derive(latitude {latitude});
derive(longitude {longitude});
derive(tropospheric_NO2_column_number_density [Pmolec/cm2])”
reduce_operations=“squash(time, (latitude, longitude, latitude_bounds,longitude_bounds));bin()”

files_in=“S5P_RPRO_L2__NO2____20200301T*.nc”

mean_no2=harp.import_product(files_in, operations, reduce_operations=reduce_operations)
But it throws error where I am doing wrong?

CLibraryError Traceback (most recent call last)
~\AppData\Local\Temp\ipykernel_5556\3427238298.py in
1 # B5: averaging
----> 2 mean_no2=harp.import_product(files_in, operations, reduce_operations=reduce_operations)

C:\ProgramData\Anaconda3\lib\site-packages\harp_harppy.py in import_product(filename, operations, options, reduce_operations, post_operations)
1157 if _lib.harp_import(_encode_path(file), _encode_string(operations), _encode_string(options),
1158 c_product_ptr) != 0:
→ 1159 raise CLibraryError()
1160 if _lib.harp_product_is_empty(c_product_ptr[0]) == 1:
1161 _lib.harp_product_delete(c_product_ptr[0])

CLibraryError: could not derive variable ‘latitude {latitude}’
Thank You for your quick response.