deployment - Build C# .NET 3.5 project fails with psake but succeeded with msbuild -

i'm trying create build scripts psake our company c# project in .net 3.5, when run it, fails errors

default parameter specifiers not permitted 

i google out , looks problem of .net 3.5 not allow default parameters in functions.

however strange same project built msbuild.exe has succeeded. tried set $framework variable of psake '3.5x86' , '3.5x64' none of helps.

do have idea wrong psake or if there secret variable i'm missing?

my psake script:

$scriptdir = split-path -path $myinvocation.mycommand.definition -parent  $framework = '3.5x86'  $serversln = $scriptdir+'\..\server\server.sln' $clientsln = $scriptdir+'\..\client\client.sln' $outdirserver = $scriptdir+'\..\binaries\server' $outdirclient = $scriptdir+'\..\binaries\client'   task default -depends full task full -depends clean, buildserver, buildclient #, buildaccs, deployrelease  task buildserver {   #framework '3.5'   exec { msbuild $serversln /t:build /p:configuration=release /v:quiet } }  task buildclient {    #framework '3.5'   exec { msbuild $clientsln /t:build /p:configuration=deploy /v:quiet }   exec { msbuild $clientsln /t:build /p:configuration=release /v:quiet } }  task clean {   write-host cleaning    if (test-path $outdirclient)      {            rd $outdirclient -rec -force | out-null     }    if (test-path $outdirserver)      {            rd $outdirserver -rec -force | out-null     } } 

output of script:

$scriptdir = split-path -path $myinvocation.mycommand.definition -parent  $framework = '3.5x86'  $serversln = $scriptdir+'\..\server\server.sln' $clientsln = $scriptdir+'\..\client\client.sln' $outdirserver = $scriptdir+'\..\binaries\server' $outdirclient = $scriptdir+'\..\binaries\client'   task default -depends full task full -depends clean, buildserver, buildclient #, buildaccs, deployrelease  task buildserver {   #framework '3.5'   exec { msbuild $serversln /t:build /p:configuration=release /v:quiet } }  task buildclient {    #framework '3.5'   exec { msbuild $clientsln /t:build /p:configuration=deploy /v:quiet }   exec { msbuild $clientsln /t:build /p:configuration=release /v:quiet } }  task clean {   write-host cleaning    if (test-path $outdirclient)      {            rd $outdirclient -rec -force | out-null     }    if (test-path $outdirserver)      {            rd $outdirserver -rec -force | out-null     } } 

the $framework variable deprecated in latest versions, should use framework function instead. apparently not work. looks bug in psake.