have you got an example of your script.
If you are sure the script is running then it is not a problem with Set-executionpolicy.
If you are targeting a 64-bit system it may be an idea to use powershell in the SYSWOW64 windows directory not the System32
Also get it into a variable and test the contents when it fails?
$Command = "C:\Fullyqualifiedpath\plink.exe"
$Parms = "$server -l $user -pw $password -t "echo -e '$password\n"
& "$Command" $Parms | sudo -S /etc/init.d/$servicename $action"
I found the problem. It was actually just the service account used for solarwinds. I needed to change the logon account of "Solarwinds Orion Module Engine" rather than "Solarwinds Alerting Service V2". Once I changed this I was able to use Powershell 64 and 32bit just fine.