REST API Query Option

Hi,

While i use the following query it does not return proper result.

• https://<Server name>/sites/Projects/_api/ProjectData/Tasks?filter=TaskIsMilestone eq 'true' 
• https://<Server name>/sites/Projects/_api/ProjectData/Assignments?filter=ResourceId eq guid'" + ResourceUID + "'

Can someone point out how to write the same as i am following this link for the same without luck. 

https://msdn.microsoft.com/en-us/library/gg309461.aspx#BKMK_filter

Thanks, Parth