Making the Input Paramters of web service task dynamic inside SSIS pacakge

I have a call to a web service task inside of a for loop container in a SSIS 2008 package. I need t开发者_开发百科o pass a date as part of the web service input parameters. The date is calcluated based on a variable in inside the for loop. I can calculate it as an expression, but I don't know how to make that expression the input parapmter. Is there another way to accomplish this?

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I figured it out. I had to create a variable that had EvaluateAsExpression set to True. Then I created my expression

Then I passed the expression as the input parameter