PowerShell script not working on server - asp.net

Question

I have a simple PowerShell script in which I try to write some log data.
The script that's not working:
Add-Content -Path C:\temp\logg.txt -Value $file.FullName
This line I placed in the middle of the script and I never get any text in the logg.txt. The Script executes fine except this, it compiles some files to a zip file.
This is on a Windows server.
If I, however, run the same script on my local machine, Win7, it does work!?
So I think it must be something with the server but I can't figure it out. Am using -ExecutionPolicy Bypass when I run the script.
EDIT: more info.
The script is called from an ASP.NET webpage:
Process.Start("Powershell.exe", "-ExecutionPolicy Bypass -Command ""& {" & destinationFolderRoot.Replace("\\", "\") & "\scriptParameters.ps1}""")
BaseZipScript:
function New-Zip
{
param([string]$zipfilename)
Set-Content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
(dir $zipfilename).IsReadOnly = $false
}
function Add-Zip
{
param([string]$zipfilename)
if(-not (Test-Path($zipfilename)))
{
Set-Content $zipfilename ("PK" + [char]5 + [char]6 + ("$([char]0)" * 18))
(dir $zipfilename).IsReadOnly = $false
}
$shellApplication = New-Object -COM Shell.Application
$zipPackage = $shellApplication.NameSpace($zipfilename)
foreach($file in $input)
{
$zipPackage.CopyHere($file.FullName)
Add-Content -Path "C:\temp\logg.txt" -Value $file.FullName
Start-Sleep -Milliseconds 750
}
}
scriptParameters1:
. "C:\temp\multiDownload\baseZipScript.ps1"
New-Zip c:\temp\multiDownload\user379\2016-09-15_14.39\files_2016-09-15_14.39.zip
dir c:\temp\multiDownload\user379\2016-09-15_14.39\tempCopy\*.* -Recurse |
Add-Zip c:\temp\multiDownload\user379\2016-09-15_14.39\files_2016-09-15_14.39.zip
Start-sleep -milliseconds 250
exit
As I said earlier the script works on local machine and also on the server, e.g. the files are being zipped, except that on the server nothing is logged in logg.txt.
Though the logg.txt works and exists on the server because the webpage also log some info there and that is being written.
Update:
As the comments guessed it was as simple as write access to the file. Though, it is kind of wierd because all files are created from the webservice if they doesn't exists? Any how, it works now. Thx! : )