Question: Plotting direction fields for Differential Equations

I am tyring to plot a directional field for a few simple differential equations.  I keep getting an invalid range error for the independent variable.  I am new to Maple and have been using the program for a couple of days.  Can someone help me with this?  I know the answer is probably simple but I can't figure it out.

> dfieldplot(d*y(x)/dx = (1-y(x)^2)/(2+.5*x^2), y(x), x, x = -2 .. 2, y = -5 .. 5, arrows = SLIM, color = black, dirfield = [5, 5]);
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Error, (in DEtools/dfieldplot) invalid range for independent variable

> dfieldplot(d*y(x)/dx = x*sin(x)/(1+y^2), y(x), x, x = -6.15 .. 6.15, y = -5 .. 5, arrows = SLIM, color = black, dirfield = [10, 10]);
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Error, (in DEtools/dfieldplot) invalid range for independent variable
 

Thanks to anyone who can help.

Bob Kelley