Missing parameter, no chart displayed

I've got this problem: (with Reporting Services 2005)

I've got a report with a chart with some values that are needed to get the chart displayed.
If one of this parameters is missing (not selected) the program doesn't display the report (it shows a blank page)
Is it possible in this case to get instead a textbox with a message requiring to select the missing parameter (if I insert a textbox below the chart in the layout, this textbox isn't displayed if one parameter is missing)

ps sorry for my poor english

thanks in advance for your helpI believe what you want can be accomplished by making sure each parameter is set to NOT allow blank value. Just go to "Report" -> "Report Parameters" and make sure the "Allow blank value" checkbox is unchecked for each parameter. Then, the report will not be generated and a popup box will be displayed if the user doesn't enter a value.|||

Thank you for your answer.
But the problem is that I would like to display a warning to the user to suggest him to select the missing parameter (in my case choosing from a scrolling menu).
The parameter is multivalue so i would like to avoid to displaying a default value, but I would like the user to choose.
The application does not seem to allow this.
In fact if I add a textbox, it's not displayed unless also the chart is displayed.
So if the parameter is missing, no chart will be displayed and so the textbox too.
No object is being shown unless all the parameters are selected and only in this case the chart can be displayed... but as I said I would like to display this warning when a parameter is not selected.
How can I do this?

ps: sorry if I'm a little redundant

|||

If what you want is a message to be displayed to the user to choose a value, then you should be able to accomplish this by unchecking the "Allow blank value" option as stated above.

For example, if there are two parameters say "Type" and "Subtype" but the user only selects "Type" and leaves "Subtype" blank, then once the user clicks "View Report" a popup message will be displayed to the user saying...

"Please enter a value for the parameter 'Subtype'. The parameter cannot be blank."

|||Thanks for helping me :)
The pop up appears but I would like this message to show in the report layout but BEFORE ckliking on "view report"...just a simple generical message saying to the user something like "please choose a value for the X parameter and THEN click on view report"
The message is a sort of "guide".
I thought I can do this by placing a textbox but it seems that the textbox is linked to the chart (no chart no textbox)...i know it seems a stupid problem but unfortunatly I was asked to do this work this way.|||

Well, there is one way to generate a textbox in the report even without having a paremeter selected. Simply make sure all parameters are set to "Allow blank value" and "Allow null value". Then, create a textbox where the visibility is set to an expression, where it will only be displayed if any parameter is blank. Also, be sure to make the rest of the report items the opposite of that expression, i.e. they are only visible if all values are entered.

For example, Visibility -> Hidden = Iif(IsNothing(Parameters!ParameterName.Value) OrElse Parameters!ParameterName.Value.Equals(""), False, True)

This way the textbox will show up in the report whenever the user doesn't select a parameter value. However, the report will not autodetect the new values entered until the user clicks "View Report."

Good luck!!

|||Hi, thank you for your answer.
Unfortunatly I don't seem to be able to set "allow null value" for the parameter I'm interested in, cause the application says that the properties for that object are invalid.
That object is a multi-value string available values from query.
So your suggestion does not work. :(