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.

[Larz60+]

Is this join statement correct? (look like 'folder' should be replaced with 'name')

inP = os.path.join(mDir,folder)

[CashMunny]

yes. it is correct. i'm now getting a new error, however:

Error:
Traceback (most recent call last):
  File "C:\Python27\ArcGIS10.2\Lib\site-packages\pythonwin\pywin\framework\scriptutils.py", line 323, in RunScript
    debugger.run(codeObject, __main__.__dict__, start_stepping=0)
  File "C:\Python27\ArcGIS10.2\Lib\site-packages\pythonwin\pywin\debugger\__init__.py", line 60, in run
    _GetCurrentDebugger().run(cmd, globals,locals, start_stepping)
  File "C:\Python27\ArcGIS10.2\Lib\site-packages\pythonwin\pywin\debugger\debugger.py", line 654, in run
    exec cmd in globals, locals
  File "N:\Common\Script\Drivers\make_zips.py", line 1, in <module>
    import zipfile as zp
  File "C:\Python27\ArcGIS10.2\lib\zipfile.py", line 752, in __init__
    self.fp = open(file, modeDict[mode])
IOError: [Errno 22] invalid mode ('rb') or filename: ' P:\\2018\\Archive\\CO_001_Model.zip'

[CashMunny]

Thank you Buran. Is there away to edit my post so I could have included the traceback?