Implementing rainfall across a planar area

This may be a trivial issue, but it has stumped me.

I am trying to create a 2d planar regional groundwater flow model of an aquifer for my MSc dissertation. The aquifer has very little water inputs, the only recharge comes from rainfall. For reference, I am using the ogs.exe and viewing my results in GINA.

I know how to implement rainfall across a polyline. I can make this work. However, when I try to implement the rainfall across the whole domain, OGS stops running when it gets to the ST file. I got around this issue by implementing the rainfall across a surface. However, when I run this, OGS says that the surface is not complete and the polylines aren’t linked. I have checked this at least 1000 times and as far as I can see, the polylines are connected. I am stumped.

As a result of these two issues, I cannot get water into the system via rainfall. Does anyone have any tips? Am I missing something really simple?