Simulink get rid of error that block doesnt support variable size input

Dear all I am using Simulink and its great except this error who i cannot get rid of

Simulink cannot propagate the variable-size mode from the output port 1 of 'Framing/FrameGenerator/AddEscapeCharacter' to the input port 1 of 'Framing/FrameGenerator/Buffer'. This input port expects a fixed-size mode. The variable-size mode originates from 'Framing/FrameGenerator/AddEscapeCharacter/Switch'. Examine the configurations of 'Framing/FrameGenerator/Buffer' for one of the following scenarios: 1) the block does not support variable-size signals; 2) the block supports variable-size signals but needs to be configured for them.

I want to generate frames who are buffered in a buffer, and the buffer block cannot accept variable size input ??! Is there any quick workaround this except not using buffer block ? If this is not possible i think Simulink is quite weak to deal with variable size signals