Connecting multiple Collect Value outputs to Cell Statistics + ModelBuilder ArcGIS10.1

I have developed a model that collects values through a number of integrated sub-models. I was hoping to use Cell Statistics to run an analysis on the results from each of the sub-models. It will work properly when I have Output Values from one of the sub-models connected but I can't seem to connect the results from more than one model.

For instance, I have the results from ModelSoils connected but can't connect ModelEnv at the same time. I have tried connecting and selecting 'Input rasters or constant values' but it won't connect.

Any suggestions on what I am missing here? Thanks Justin