Unable to use ui.Chart.image.series() in jupyter lab

Question

A mistake occured when extracting NDVI and plotting trendlines with Sentinel 2, running S2_chart = ui.Chart.image.series() gives an error saying ui. is not defined. I'm using Windows, Python 3.12.3, ipygee-Version: 0.0.18, geetools-Version: 1.3.0, jupyeter lab extension manager is also active, lab-version3.0 and note book-version6.5.4. version6.5.4

Here is the entire codes:

import ee
import geemap
geemap.set_proxy(port='my port')
Map = geemap.Map(basemap = 'Esri.WorldImagery')
shp_path = r'E:\postgraduate study\GIS文件\祁阳市.shp'
shp_fc = geemap.shp_to_ee(shp_path)

geometry = shp_fc
Map.centerObject(geometry, 9)

colorizedVis = {
'min': -0.8,
'max': 0.8,
'palette': ['blue', 'white', 'green']
}

def maskS2clouds(image):
qa = image.select('QA60')
# Bits 10 and 11 are clouds and cirrus, respectively.
cloudBitMask = 1 << 10
cirrusBitMask = 1 << 11
# Both flags should be set to zero, indicating clear conditions.
mask = qa.bitwiseAnd(cloudBitMask).eq(0).And(qa.bitwiseAnd(cirrusBitMask).eq(0))
return image.updateMask(mask).divide(10000).set(image.toDictionary(image.propertyNames()))

def createNDVI(image):
ndvi = image.normalizedDifference(["B8", "B4"]).rename('NDVI')
return image.addBands(ndvi)

S2_COL = ee.ImageCollection("COPERNICUS/S2")
.filterDate("2021-01-01", "2021-12-31")
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
.filterBounds(geometry)
.map(maskS2clouds)
.map(createNDVI)
.select('NDVI')

#The mistake occured here:
S2_chart = ui.Chart.image.series({
'imageCollection': S2_COL.select('NDVI'),
'region': geometry,
'reducer': ee.Reducer.mean(),
'scale': 500
}).setOptions({
'interpolateNulls': True,
'lineWidth': 2,
'title': 'NDVI Time Series',
'vAxis': {'title': 'NDVI'},
'hAxis': {'title': 'Date'},
'trendlines': {0: {'title': 'NDVI_trend', 'type': 'linear', 'showR2': True, 'color': 'red', 'visibleInLegend': True}}
})
print(S2_chart)

I tried to upgrade the lab, the notebook, the ipygee,and enable the extension,but made no sense.

Thanks for your attention very much!