error message : undefined reference to 'gst_element_link_pads_full'

hi
can anybody help me about this error message "undefined reference to 'gst_element_link_pads_full'"
how does this error happen?
thanks a lot :)

Firstly, this is nothing to do with Qt.

it happens when you tell the compiler that gst_element_link_pads_full exists, and in your code you try to use that method, but you have not implemented it properly, or told the linker where to find the method in another library.

Thank you very much, but this error message only happen when i move my project from windows to unbuntu. It can successfully compile in windows. How could this happen?

you didnt move everything or you are not correctly building your project (that includes incorrect build environment)

edit:
or you didn't build/install all required libraries on *nix.

do you have libgstreamer on ubuntu?

I moved whole project to ubuntu and delete .user file. Could you tell me what is incorrect build environment?

I didn't have libgstreamer on unbutu. After I install libgetreamer, it still show the same error message. Do you know why? Please help me! Thanks a lot. :)

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Added after 21 minutes:

The problem is solved, but I don't know why. The solution is that I change the build configuration from Qt 4.8.1 to Qt 4.8.0 and it works. Do you know why? Thank you very much.
:)