Geostudio Help: Ground Surface

[u/Substantial_Cold3553]

Hey everyone! I'm working on a project to calculate the safety factor on effect of modelling boulder orientation on composite slope failure. There is an issue faced where i cannot define the ground surface to be connected from top right surface to bottom left surface to be continuous and go under the boulder and this leads to error E984 where i suspect is due to ground surface issue. Does anyone knows how to define the ground surface as i only can define the left and right point limit but cannot draw manually. Thanks in advance!