The Map Algebra expression could not be correctly evaluated. This might happen if there are any syntactical errors in the expression or if there were any invalid characters in the paths or names of the datasets. Having space characters in the paths may also cause a problem if they are not quoted properly.
Ensure that you are using the tool correctly and that you have specified the correct input and output paths. Also, make sure that paths that contain spaces are quoted correctly. Be careful when using spaces in the path.