Launch Powershell script with specific parameters from Visual Build

[teognost]

Hello
I need to launch Powershell script with specific parameters from Visual Build.In Input section of the powershell step if i write the parameters as values (File1,File2,File3) everything works ok.But if I want to provide just some parameters and use option "Provide standard input from a string" there is no parameters passed,they remained with empty values.I want to specify into the Powershell step just some parameters and others to remain with default values.See the bld file attached with step1 working ok (all params are passed) and step2 where no param is passed from the input string.