Accessing pandas datframe within function returns an Attribute error: 'function' object has no attribute 'loc'

I wrote a script to update a pandas dataframe by accessing the relevant index using .loc and assigning a desired value to it. This worked fine, but as I put these lines of script into a function which uses the dataframe as an argument, I encountered an Attribute error.

I have passed a dataframe into the function as an argument. The function uses .loc to access an element of the dataframe and modify it. The dataframe however is not able to call the .loc function.

Code lines for function (Please see last 2 lines)

def DeltaCalc(dfComponent,code):
    
    ClimateList=dfComponent.Climate.unique() #Finding unique climates
    TypologyList=dfComponent.Typology.unique() #Finding unique typologies
    CompCodeList=dfComponent.CompCode.unique() #Finding unique component codes
    
    dfDelta=dfComponent[['Climate','Typology','CompCode','RunCode','MaxOT','MedianOT','MinOT','MaxMRT','MedianMRT','MinMRT','TPI','Comfortable','Cooling_unmet','DDH_Cooling','Heating_unmet','DDH_Heating','DDH','DDHSavings']].copy
    dfBaselineList=dfComponent[dfComponent.CompCode==code]

    for i in range(len(ClimateList)):
        if ClimateList[i]=='Cold': #Cold has a different baseline index
            continue
        for j in range(len(TypologyList)):
            dfBaselineTemp=dfBaselineList[(dfBaselineList.Climate==ClimateList[i])&(dfBaselineList.Typology==TypologyList[j])] #Temporary variable storing Baseline for that Climate and Typology combination
            for k in range (len(CompCodeList)):
                idx=dfComponent[(dfComponent.Climate==ClimateList[i])&(dfComponent.Typology==TypologyList[j])&(dfComponent.CompCode==CompCodeList[k])].index.values
                idx=idx[0] # index.values returns a list. Converting to integer
                dfDelta.loc[dfDelta.index==idx,'MaxOT']=dfBaselineTemp['MaxOT'].values-dfComponent.loc[dfComponent.index==idx,'MaxOT'].values 
                dfDelta.loc[dfDelta.index==idx,'MedianOT']=dfBaselineTemp['MedianOT'].values-dfComponent.loc[dfComponent.index==idx,'MedianOT'].values

Code lines for function call

dfDeltaWall=DeltaCalc(dfWall,0)