Reporting Services provides some nice options to allow user’s to feel like they are interacting with the data, by expanding lower levels of detail when they click on the plus (+) sign in the report’s tablix. You can also set the initial Toggle state of report items as expanded i.e. (-) sign. There is a catch though in that when you Show your initial state as expanded, the items may expand correctly but the toggle sign appears reversed (i.e. + instead of -).
Nice solution to the problem demonstrated Here.
popbi.wordpress.com 
Thanks a lot! Brief and very useful.
Thanks a lot for leaving the link to the SQLChick site as well.
Thank you. I was wondering how to fix this.
Thank you very much for pointing out this InitialToggleState property.
My InitialToggleState is conditional and I made it work with this expression:
=iif(Parameters!TrUnVisible.Value = false, true, false)
First I tried
=iif(Parameters!TrUnVisible.Value = false, Expanded, Collapsed)
because Expanded / Collapsed were the values I could choose from, but that condition
doesn’t work. Wonder a little bit why so, but the main thing is I made it work
with your help.
Thanks! This has bothered me for a long time… obviously not enough to figure it out, but enough to be glad for the solution
Thank you ! Saved me a lot of time !
Ive gone months with thinking this was just a quirk with SSRS, finally had someone call it out today so thought I would see what was out there. Nice to know it can be changed, and it’s such a quick and simple fix. Thanks!
Great post, had the exact problem, and worked through this in about 15 to 20 minutes. Many thanks.
Excellent! Very clear and to the point!