python zipfile.ZipFile makes zip file but can't add folders to them

[CashMunny]

I'm trying to use zipfile.ZipFile to create a zip file based on folders in a main path and then send those folders to their respective zip files. The zip files are being created but when I try using write(input, 'a') nothing is added to the zip file:

    import zipfile as zp 
    import os
    
    
    # main directory containing folders to be zipped and archived
    mDir =  r"P:\2018"
    
    # ouput archive directory to conatin compressed zip files
    oDir = r" P:\2018\Archive"
    
    # get list of folders to archive
    inlst = os.listdir(mDir)
    
    # exclude the Archive folder from inlst
    inlst = inlst[1:]
    
    # loop through the list of folders
    
    for folder in inlst:
    	name = os.path.join(oDir, ("{0}{1}".format(folder,".zip")))
     	inP = os.path.join(mDir,folder)
    
     	# make a zip archive for each folder in mDir to go into the "Archive" folder
    
    	with zp.ZipFile(name,'w') as myzip:
    		myzip.write(inP)
    
    	# add current folder to current zip archive that was just creted in previous step

        with zp.ZipFile(name,'a') as myzip:
    		myzip.write(inP)

I'm writing this to automate some house cleaning and save space without deleting anything in case we ever need to retrieve a folder. It's my first time working with zipfile so I'm sure I'm missing something. My thought was it works similar to open(file, 'w') as f, f.write("something") where I'm creating a new file with 'w' and then adding to it with 'a'.

Please tell what I'm missing so I can add the folders to the respective zip files or if I'm going at this the wrong way.