Having Trouble Passing Vars between forms - powershell

Question

im working in powershell studio
im trying to pass a string from mainform to secondform
and the var stays empty
[MainForm]
Param (
[Parameter(Mandatory=$false)]
[String]$computer,
[String]$UserName
)
$OnLoadFormEvent={
#TODO: Initialize Form Controls here
# try{
# Import-Module ActiveDirectory
# }
# catch{
# $ErrorMessage = $_.Exception.Message
# [System.Windows.Forms.MessageBox]::Show($ErrorMessage)
# }
}
#
##region Control Helper Functions
#
#endregion
$buttonOK_Click={
#TODO: Place custom script here
if ($checkboxComputer.Checked) {
$computer = $textboxinput.Text
Call-Computer_Form_pff
}
if ($checkboxUser.Checked){
$UserName = $textboxinput.Text
Call-User_Form_pff
}
else{
$ErrorMessage = "You Must Select At Least One Checkbox"
[System.Windows.Forms.MessageBox]::Show($ErrorMessage)
}
}
[SecondForm]
$FormEvent_Load={
#TODO: Initialize Form Controls here
try {
Call-MainForm_pff -computer $Computer
$computerSystem = get-wmiobject Win32_ComputerSystem -ComputerName $Computer
}
catch{
$ErrorMessage = $_.Exception.Message
Write-Host $ErrorMessage
# #[System.Windows.Forms.MessageBox]::Show($ErrorMessage)
}
}
from what i read it should work when i put in on the mainform's param section and call it this way from secondform:
Call-MainForm_pff -computer $Computer
can anyone help me with this?